[John Bedtelyon]

With the exception of two pair, if you flop a set you won't be folding to a river bet if you don't hit a boat because you'll have a straight and will chop the pot (not including the possibilty of royals) This doesn't mean you won't be laying down a set as underboats are very vulnerable and almost worthless (almost.) If you have two pair, no straight and the board is paired I doubt you'll ever have a read well enough to call a river bet since you will easily lose to the straight or more than likely the boat.