Updated: Oct 17, 2021
Conventional wisdom states that bluffing with a pocket pair is a bad thing. Pocket pairs have only 2 outs, if they're behind in a hand it's very difficult to improve. The hands that your opponent calls with also have bundles of equity against your small pocket pair. So even though you could be ahead in hand value, you can still be behind in equity (% chance to win) when bluffing with such a small pocket pair.
However, poker solvers are addicted to bluffing with 22, 33 and other smaller pocket pairs. Is the conventional wisdom wrong? Do the solvers know something that we don't? or, is it time the we updated how we think about bluffs in poker?
Small pocket pairs do have a few tricks up their sleeve when played as a bluff and when you have an abundance of hands to choose from to bluff with, they make much more sense than a random hand to bluff with.
Bet then Fold.
One issue with selecting a hand such as a gut-shot straight draw to bluff with, is that the hand has a fair amount of equity still. It has 4 outs to the nuts to hit by the river and would benefit from realising this equity. If we were to be x/raised with a gut-shot straight draw after betting, we wouldn't quite have the implied odds to call (most of the time) and we are being denied the realisation of a large amount of equity.
Small pocket pairs don't have this problem, they have such little equity against a players raising range that a fold becomes easy. No issues with equity realisation or folding a good hand at all. When you start paring this fact with the following concepts like the unblocking of folding ranges and what exactly clean outs are, 22 starts to look like a much more appealing bluff.
Unblocking a Folding Range
The concept of blockers is a relatively advanced topic, made more complicated when we start talking about unblockers. In poker, you can block your opponents good hands by having specific cards in your own hand. For example, if you have the Ace of Hearts, then it would be impossible for you opponent to have the nut-flush in hearts.
On the flip side to this you can unblock certain hands by you not having that specific card. Now you not having the Ace of Hearts makes your opponent having the nut-flush more likely. This becomes especially important when thinking about bluffing combinations. While its good to block your opponent from having good hands, it's as good if not better to unblock hands that your opponent can fold.
This is the reason bluffing with missed flush draws is ill-advised. Ideally, your opponent had the flush draw and will be forced to fold to your bet. When you have said draw, you are increasing the chance that your opponent will have a hand that he can call with. In other words, you are blocking his folding range.
What Makes Small Pocket Pairs Such Good Unblockers?
The goal of a bluff is to make our opponent fold a better hand or fold hands that have a large amount of equity against us. We would prefer to increase the frequency at which we generate a fold with our bluffs. The main problem with picking random hands to bluff with is that they can block weak hands in your opponents range. These hands include our opponents 2nd, 3rd pairs, and hands that have good amounts of equity still such as weak draws.