if u bet 4x the BB preflop and are in position and have only 1 caller, u should bet the flop if he checks. lets say u have 1500 chips and the blinds are 25/50. u raise to 200 and get 1 caller. the flop is k high and and he checks. u should bet since the pot is 400, and a bet of 200 will usually win it outright. yea the K is a scare card and he may have it, but if u raise and he calls, that means he will probably willing check the turn and the river, (unless he flopped a big hand llike trips). but if u dont bet your giving him a chance to outdraw u. if an ace flops, and he checks, you should probably check. chances are he called with a weak and and wants to check call u down.