Well, oskar what you are talking about is unexploitability vs. exploitability.

When you play to exploit your opponent you are playing an exploitable strategy yourself. When you bet/fold top pair on the flop vs. a fish, you're exploitable vs. bluff raises, but a passive fish doesn't think about bluff raising you so you keep on running the bet/fold line because your overall strategy exploits the lack of bluff raises by the fish.