Flopping four of a kind...Extracting?

[TomBrooks]

Hi Daemon,
I actually had only three guys trapped and there was only one I would have been forcing to face two, and he folded anyway. I was hoping the flop bettor would bet out again on the turn and I would have raised there, trapping the field for a big bet and hoping someone would make some kind of hand they would call to showdown with. Raising the flop would usually insure that flop bettor would not bet out again on the turn so I just called. You can't be sure just calling a flop like this is optimal, but I think usually it is. There is no fear of giving a free or cheap card at least.