there's a brilliant piece in the Cleveland Plain Dealer, about the shadiness of financing an MLS venue... It's by a reporter named Bob Roberts. http://www.cleveland.com/sports/plaindealer/index.ssf?/base/sports/1075890869204061.xml
I'm not sure this is really MLS-specific. It's just talking about sports teams bilking their towns for millions. You should read articles in the Bay Area about the Raiders or in San Diego about the Chargers. The Charges have been raping the people of San Diego for years. And they suck, too. Plus they've been threatening to leave for years now. Anyway, with any talk of expansion, everyone should have their fingers crossed.
I think one of the reasons city's take the hit on paying for stadiums like that is because it gives the people something to do. Also by paying it, it brings people into the city where they can be closer to their favorite sports team. This in return brings in more revenue through city taxes.