My suggestion would be to talk with many realtors before signing. When you get construction work done, you should get three quotes. I’d talk with at least 5 agents.
Most people just go with the first one they meet, or they just go off a recommendation. Check the BBB, talk with former clients of theirs, even ask each realtor about the other ones you have talked with – see if you can dig up any dirt.
As I mentioned in another post, I know one that is certainly worth an initial consultaion.
Another thought for buyers – consider a buyer-only agent. They have a little different take on the market because they deal exclusively with buyers and they don’t have listing business to get in the way.