Custer has said that he sometimes folds when in a marginally +$EV spot, to save time/attention for other tables or something like that. This could be the reason he folds.

And I've tried to raise with Ax, kings with decent kickers, low pairs etc. in this spot, but I keep getting reraised all-in. [img]/images/graemlins/confused.gif[/img] Could be variance, or maybe I choose all the wrong opponents to do this.

Maybe calling is best. Almost everybody folds to a bet on the flop unless they hit something fairly good. (player dependent of course)