Maybe you are laying your SC'ers down to fast when you hit a straight or flush?
Your hand might be disguised so good that someone with TP/2pair/set plays very aggressive thinking he is ahead, so you are laying your hand down thinking he is holding a higher straight/flush.

Edit: You cant expect to make huge profits with SC'ers I think. You just have to play them, because if you dont you are basically playing only PPs and Paint, which makes you very predictable.
Playing SC's is good to mix up your game, while still having the potential for flushes/straights.