Deviations in a typical loose passive game

I pretty much agree with your approach, assuming you're talking about the early stages of a tournament when everyone's relatively deep.

Once the stack sizes start getting shorter the value of those implied odds hands goes down, and the value of high card combos that can make good top pair hands goes up.

When stacks are shorter it also becomes a lot more costly to do things like limp behind. Even opening too wide with a raise can backfire if you end up getting called a lot, and having to fold, usually to bigger stacks that can apply pressure postflop.

Make sure not to fall into the trap of bleeding a significant amount of chips. As you get shorter you generally want to play aggressively, and be more willing to go all the way and get your chips in the middle when you flop a decent piece.

Conversely as you get shorter you can often defend wider in the BB. The reason is that your equity realization goes up. If you flop a decent pair or draw, you can often just get your chips in the middle, and you're less likely to get blown off your hand.

All this is assuming you're not close enough to the bubble for ICM to be a major consideration.

Anyway, good luck on the tables!

Another common situation in these games that I am unsure of how to handle is when I am in early-ish position, there has already been a sticky limper and I am dealt a hand that's near the bottom of my opening range from that position, say AJo, Q9s, JTs.

What's the best way to play these? I presume that folding is too nitty. Iso-raising with all 3? Iso-raising with the AJo and limping behind with the others?

I will typically tighten up, and fold the bottom of my normal opening range if someone has limped, but it depends a lot on the limper and the table dynamics.

Do they limp strong hands or are they capped at very weak hands when they limp? If they're limping some stronger hands you want to tighten up more.

Also, what are the other players on the table likely to do? If you have aggressive 3-betters behind you generally want to tighten up more.

How likely is the hand to go multiway? Usually in these games, if you raise the likeliest result is that one or two other players along with the initial limper all call. If that's the case you want to play hands that play well multi way.

At 100 bb deep I would likely fold AJo and Q9s but might open JTs. JTs can make some straights and flushes that cooler the type of hands people flat you with, and you will flop some strong draws that can put a lot of pressure on weak ranges. If you flop a top pair type hand you'll want to play it cautiously though.

At 20 BB I would likely open the AJo, fold the Q9s and maybe open JTs. When you're that short it's less costly to flop an ace and be out kicked. If AJo makes top pair you can pretty happily get the money in, and if you're out kicked it's only 20 bb deep so that's pretty much a cooler whereas at 100 BB it could be a punt multiway.

This is all assuming people are calling fairly wide. In theory the ranges that over call should be fairly tight, but in practice people tend to call much wider, and also don't 3-bet enough.

Finally, what might be one of the most important considerations is how good you are in comparison to the other players postflop. I will attempt to isolate weaker players pretty relentlessly, but avoid playing pots with the best players unless I have a hand.

In a game like this, divide your range into hands you want to play heads up and hands you want to play multiway. Usually this looks like hands that flop strong 1 pairs or top two and hands that flop strong draws. Then play accordingly, it's not that difficult.

I typically move one to the left on the GTO chart with my open range and open to a larger size such as 4x due to the additional dead blind. If they are an extremely tricky limper you can mix in some min raises. And of course you can continue to complete middle strength hands on the button with other weak passive players in the blind. Vs multiple limpers you generally can also squeeze relentlessly from the BB with a strong linear range sometimes even to 6-8bb. Post flop since these players are weak passives you also get to play more "face-up" and don't follow GTO cbet frequency or sizings.

As the above posters mentioned at 20bb the strategy is different, if there is 4-5bb of dead money already then you can turn your 3bet rips in GTO into open rips vs limpers because there is the same amount of money in there and the limps are generally a weaker range

I don’t think this question has been answered with any sort of theoretical rigor.

I’ve only addressed your first question because—as you can tell by this post’s length—each is worthy of a post of its own.

To determine the EV of a SB complete in a limped pot, you can use the following equation:

EV = Equity * Realization * Pot * P(Flop) – Call

Let’s break that down to each of its terms in order of complexity:

EV:

This is self-explanatory. You will want this to be greater than or equal to 0 to not fold.

POT

Pot = Ante + 2b + n*b, where b=big blind and n=number of limpers (2B is for you and the BB)

P(Flop)

This is the probability you see the flop, so P(Flop) = 1-r, where r=BB’s ISO frequency

Eq

For Eq, use an equity calculator to compute a given hand’s equity given each player’s range, using their limp frequency, but remembering to subtract the top of their range based on their raise frequency. For example, if someone plays 40% of hands from every position and raises 10%, then you will want to take the top 40% of hands and deduct the top 10% of hands.

Realization

Equity realization may seem like more of an art than a science, but there are reasonable extrapolations that can be made from theory. For example, you can:

1) Find the closest possible corollary preflop solutions (ie: hand charts). Since there aren’t a lot of solutions for limped pots, the next best thing would be a chart that has a cold calling range for SB facing a raise and at least one call. Since that’s a pretty uncommon theoretical configuration, you might have to use BB multiway defense ranges. Then, HU scenarios would be the next corollary after that.

2) Plug in each of the numbers in the equation above. If EV isn’t provided by the chart/solver, you can look at the hands that mix call and fold, as those can be assumed to have 0EV. For places where you’re facing a single raise, use BB’s GTO squeeze frequency as the r in 1-r.

3) Adjust for the differences between the solution and your actual scenario. For the raised pots, perhaps refer to charts with double the stack depth to make the relative SPR more similar to a limped pot. For charts in the BB you may have to adjust for having 1 seat more favorable position. In order to know what adjustments to make here you may have to take a step within the step where you compare closest corollary solutions where the extrapolation you’re making is the only difference, then follow all these same steps to estimate what kind of difference that one factor makes.

4) Solve for EQR for different hand types; eg: offsuit broadways, pairs, suited disconnected hands, suited semi-connected hands, suited connected hands, offsuit connected hands.

Skill advantage may also be worth something like 10-20% of EQR, but #1 this is where we start to stray from theory and #2 is that I think the cases where skill advantage can account for large EQR gains in these sort of circumstances are uncommon. Either a) you need to be exceptionally skilled in MW pots—I’d set the bar at being able to execute 0EV+ bluffs in these pots with some regularity—in order to have a significant number of pots where you are overrealizing, and/or b) your opponents are so bad that the pots on the tail end of your distribution are so large that they have a significant impact despite not being significantly frequent –I’d set the bar at something like stacking off 20 times the current pot with a single pair, which might not even be possible at most stack depths.

You’ll want to do this for at least a few different stack depths and blind/ante structures to get a good sense of what the bottom of your call range is given some different factors. I’ve done a pretty thorough analysis for different deep-stacked cash games, but I would not trust it to translate due to stack depths and rake, and it’s not something I would give away for free anyway.

I would kind of disagree with classifying these hands just as implied odds hands when multiway (especially weak multiway), as multiway you have such good pot odds by default that you don't really need implied odds that much, which basically lifts the stack size limits, and the main strong point of these hands is that they can compete very well multiway (though the nuttiness is a big factor, making suited aces and pocket pairs a huge preference, while suited connectors should be played with caution).

So technically in very weak loose passive games you can over- or openlimp even 10BB and less. In normal games you will just get rejammed by stronger players, while in weak games it will not happen that often, while presence of multiple habitual limpers with bigger stacks will make it tough for any stronger players to attack you specifically.

But, for the others, it doesn't mean that you should limp with weak hands, but mostly with the hands that have good chance to collect multiway pot odds if flopped well, while the hands that good heads-up but horrible multiway (especially offsuit big cards) prefer to open-raise (or open-jam if you are shortstack), in their case you usually have to size much larger to avoid passive players to heap-call and therefore comparatively tighter.

Pot odds are pot odds, sure. You've still got to consider equity realization though.

Plays like limping behind with pocket 2s off a ten BB stack are generally just not going to be profitable in the long run. You will flop a set approximately 1 in 8 times, and it may appear that you're getting the right pot odds. The problem is that you're barely getting the right odds assuming everything goes right.

Even in a relatively passive game someone will jam or raise big preflop some percentage of the time. Even passive players will wake up with hands and raise, or someone will recognize there's a bunch of dead money in the pot and raise. So when you factor in the times you get blown off your hand and don't even get to see a flop, you're just bleeding money by limping. Even when you flop a set you won't win 100% of the time. Sometimes you'll get your money in against a draw and lose.

Limping in these types of scenarios is a common leak. You might only be losing .1 BB on average, but it's still a losing play. As with most things in poker, there are always going to be exceptions to the rule. Generally though you don't want to get into a habit of limping small pocket pairs and weak suited aces when you only have a 10-20 BB stack.