That's what I've been trying to get one of my beginner friends to realize. He hates playing someone more than once since they learn his "tricks," which is what you WANT THEM TO DO. He prefers fighting randoms on ranked so he can steal a win from the element of surprise and not have to worry about them figuring him out.
The problem is, if the only reason something you do is because your opponent didn't know about it, and it would fall apart as soon as they do, then it's a bad thing to do.