If I'm 3 betting the flop, then I'm never folding - opp could easily have pair & draw, and we have outs vs two pair also. However, I prefer to just call this small raise and reevaluate on the turn. Against am aggro donk I'll check/bomb the turn if its a good card, against a more passive player I may just let him take it on the turn if he bets big.

just a VP$IP/PFR split would be nice :P