i think this is very dependent on the level of play of your opponents. at 50nl and below i saw a ridiculous amount of players stacking off with much worse than TPTK. Obviously insta shoving any flop where you have an overpair is not perfect advice, but there are very few situations where i would fold an overpair at low stakes. Also, this is an area of poker where your knowledge of your opponent is critical. If your opponent plays like an idiot, obviously you should not give his raises respect. If you know he usually plays 'logically', than you should be more cautious. There is no perfect answer but without a pretty solid read that an opponent plays decent i am usually fairly happy with felting an overpair on uncoordinated flops.