I don't play Stars yet... What does this mean? Completely confused...
On stars the fold button is always an option. So if everyone checked to you, or you are first to act in a pot you can fold whenever you want. On Full Tilt, if it's checked to you or you are first to act. The fold button isn't an option. You can only check or bet. Which you should do, you should never fold when you can see a free card.
However, some people will play suited junk. Lets say they have suited hearts, like J2 of hearts or something stupid. They are in early position and limp. They are able to see the flop cheap. Now the flop come 3h Tc Ah. Now they have a flush draw. They check, guy in LP bets, they call, turn brings Qc. Again, they check, guy bets, they call. River brings 6d. They missed and if they check, the guy in LP could be confused and check. Then you would have to show that you called all the way to the river with J2 of hearts. So, on
poker stars on the river you are first to act, you can fold, just like in a live game, you can fold at any time, doesn't mean it's the right move. On Full tilt, you would have to check and hope the guy in LP bets so you can fold.
So when someone folds out of position when they could check, you already know they are playing junk that missed the board or they where chasing a draw that missed. So folding when you can check doesn't really do you any good. Also lets say 2d came on the river instad of the 6d. Now you have bottom pair, you still think you are beat, but lets say you check, and the guy in LP figures you have an A and are going to call, while he was semi
bluffing on a straight draw with KJ. Now if you check and he checks, you win the pot.
I'm not saying never fold when you can check. But, you should be checking 99.99% of the time instead of folding.