This is an old post but interesting to answer since I hear this question from clients today...
For short sales as we are involved in, the client must use an MLS agent as required by the lender.
As far as earning a ton of money, possibly in the good ole days of a strong market (where everyone under the sun wanted to list homes so they could get a piece of the pie) this would be 'somewhat' true...but no more. Today, if an agent is earning a perceived "ton of money" it is well deserved because of the service they provide. Either thy make a transaction happen or they don't...and if they can't make it happen, they usually drop off. The stats will vary depending on the agency agreements with the agent...gross numbers can look high, but as stated by others here, once you look at the net number, the numbers deflate rapidly. Stats can be found at: http://www.bls.gov/oes/current/oes419022.htm
Tom Hinz www.shortsaletosell.com