I wish spenda would come back and discuss this, because I struggle a lot in WA/WB pots. But I try to determine BEFORE I play the flop what type of player I'm up against and what his typical reactions will be to different lines. I do know that if these two things are true, I can check behind and profit:

1. If I can be pretty sure I'm Way Ahead
2. If I can be pretty sure he'll bluff