I agree, part of fishing is finding cover, structure, or what ever you want to call it. If I mark fish on a brush pile I'm gonna fish it. Like was said earlier I wouldn't follow anyone uninvited, but if I happen to run across one and nobody is around it's fair game.
I have gone to my brush piles before and someone be sitting on it catching fish. Oh well thats a chance you take. Just move on and come back later. Just my opinion.