For me it is 10's or better excluding position, normally. I will change it according to the table but that is my cut off.
For anything below JJ, the odds
are over 50% that there will be at least one scare card on the flop. You are more than likely going to have to fire out a continuation bet when you are only going to get called by someone that is ahead of you. You have a very small chance that your hand can improve since you are really drawing to the two cards to make a set.
High PP are great because even when you don't get the third one you have better chance of an overpair and thus have added value to winning the hand. PP below JJ or 10's make you have to gamble alot more when there is an overcard (50% of the time or greater) and you don't hit your set. The power of lower PP that most of the time nobody gives you credit for them.