If you deliver shit then they keep coming back to you to fix it. Pretty sure there are major consulting firms playing that game.
It's just about what kind of clients you want to work with. If you pick any client that comes to your door and never say no then you'll end up in the race to the bottom with these large outsourcing corps.
Oh, and also, if you suck as a client, they're going to drop you and never answer your calls again.