*cough* Bullshit! You can NOT eat for 20 baht in a honesty if you are European or American especially. If you have food from a food stall at the side of the road where you might well get e coli as easily as a tasty meal, then yes you can possibly eat for 20 baht a day. But if you eat at even McDonalds it's 150 baht. But why would I eat at McDonalds or, say, KFC on Koh Samui? Because it's clean. Oh, yeah you can get really great food at a restaruant too that is clean and up to 5 star - and you pay what you would everywher else. But yeah, if you want to eat like the people who serve your food, eat, in Thailand, then it's really cheap becaue it HAS to be.
150 bahn is the absolute lowest price for renting a motor-bike on an island too, and if you're Farang (white) or Japanese/Korean esp. prepare to negotiate just to get the price a Thai would get. You WILL be ripped off the moment you blink anywhere as well. My peeps (Chinese) run most of the biz in Thailand and we're cheep as hell. Thai's are not as bad, but don't, in general, run them as well.
Don't go to Bangkok if you have asthma or some kind of lung problem - or if horrible pollution bothers you in any way.
That said the beaches are fantastic and a lot of Thais are very friendly and helpful. Try to stay away from touristy areas to get an authentic Thai experience. i.e. in Bangkok you can go to Pantip (computer city) and find orange clad Buddist monks buying all they latest in electronic conspicuous consumption, but in the country they take what the Buddah actually said seriously and knows that's not really keepking in spirit with Buddism, to say the least. And so on....