The word “cooler” is a term for a poker hand where as a rule one powerful hand has been beaten by another. Let us look at a hand like 5c-5d for example and we can see that this has definite reverse cooler potential. Now before I continue then I am not saying that you never play hands like pocket fives. However in big multi-way limped pots then you can often be on the wrong side of a big pot with hands like this. Firstly if the board pairs and makes you a boat then flushes and straights are going to pay you off less.
At the lower stakes levels then stacks will be smaller and so your opponents are more likely to stack off with non-nut hands. However, as the stacks get super deep then the fives become more vulnerable to reverse cooler situations. For example in a multi-way pot then if the flop came 10c-7d-5s and there was substantial action then the fives could be in very serious trouble here. Strong opponents would be aware of the potential for flopped sets and so wouldn’t be giving too much action with straight draws.
Hands like 10-7s and 7-5s may have called pre-flop but two pair hands are not going to donate much money to your stack either and neither will a hand like a slowplayed J-J. If the action went bet-raise-three bet-shove-call and you were the caller then you are almost certainly facing a bigger set. When players face these situations then they cry “cooler” as if it justifies everything. However, if you find that you are on the receiving end of these events too often then there may be something wrong with your hand selection or poker philosophy full stop.
At the end of the day then a hand like pocket fives normally has to make a set although this is not the case if you can be the aggressor with it. In isolation positions then hands like pocket fives can be played profitably without having to make a set and especially when you have position. Many players limp with sets in multi-way pots because of the “implied odds” and the fact that they can see a cheap flop. Sometimes it is that very “cheap flop” that can be their undoing. Players expect the world’s fair when they play hands like 5-5. They are expecting to flop a set that turns into a full house and then stack a weaker hand like a flush or a straight.
Most of the time the flushes will be weak flushes that will not stack off anyway and if there is a flush on board and a paired board then most players will fold straights. So your full house often doesn’t get paid off. All this, of course, assumes big multi-way pots. So your set of fives tends to only dominate hands like two pair and top pair and these are the hands that will not stack off lightly.
However when the big money goes in then the lower the set then the smaller the full house. What many players fail to take on board is that in PLO then a hand like K-Q-5-5 on a board of 10-7-5 rainbow would be marginal and nobody would overplay their set of fives in that situation. Omaha though is simply a version of hold’em but played with more cards. So the effect of non-nut hands is diluted but it doesn’t disappear in hold’em. When the stacks become very deep or the pot is multi-way then pocket fives do not have anywhere near the same value and are primarily looking to win a small to medium-sized pot.