99 will not win you money all the time, especially on high card boards that hit villain's 3B range a lot. Think of all the hands he 3-bets with. AKs, KQs, KJs, KK, even could have AA. Maybe he'll fire one street with something like AJo but I think pool just often gives up after you call on the flop. 99s without a set is good to call once, probably not twice.

I think the most useful thing would be to look at villain's 3B stat. 6-9% is average from my understanding (if anyone else has other opinions please feel free to chime in). Below 6% means villain is probably a Nit, you can feel pretty good about folding if they fire a second barrel. On the other hand, if their 3B stat is off the charts and something like 15-17%, then perhaps entertain a turn call if the board hits low again.

Hope this helps, as always, interested to hear what others think!

Since there are really not many good turn cards for your range at all, you should fold 9s to even small c-bets. OOP Player is ahead by a good bit! I agree with wwt2104 that calling here depends on villains 3-betting behaviour, but really against most (unknown) players, you should fold the flop (basically always).