There's one side to this that y'all are forgetting though: while what you describe may well be true for Immigration, the problem is that overstaying is in itself a crime and, if you're picked up by the police before you get to the airport, then you're in deep doo-doo. Tales of Asia has more to say on the subject:

http://talesofasia.com/thailand-overstay.htm

If you don't want to go to KL or wherever, you can probably get a visa extension in Bangkok and enjoy a free sightseeing tour of Thai bureaucracy in action.