While the system isn't perfect, in that a member can leave a bad (or glowing) review for a company that they did not hire, there is a screening system that prevents most of that. Companies that have more higher ratings go closer to the top of the front page, so those who don't offer high quality service end up being a few pages deep - and most people can find what they need on the front page.
Companies do not pay to be listed on Angie's List. They are recommended by members. We actually didn't know we were listed until 2011, when we received the Super Service Award. We have also received the Super Service Award for 2012. The badge above takes you to the member login/join page.