Hammer Bros are the last thing that's cheap once you know what you're doing. As a matter in-fact, they're totally uneffective unless you know what you're doing with them. Plus, there's ways to counter the people trying to counter Hammer Bros. I do use a Hammer Bro, and at this point, it's definitely not about spamming his attack - his special shooting ability should be used with skill, and let's not forget he has the high shooting rating. So passing him the ball when it's charged-up may also be a smart idea if he's on your opponent's side of the field.
Anyway around it, weither you hate him or you really wanna get good with him (meaning your willing to do more than spam).. send me a message and I'll be happy to help you out. Alot of the posts in this thread seem to be focused on thinking Hammer Bros spammers are a serious threat - not at all - but he's still awesome if his attack isn't spammed, too.