The main disadvantage of getting paid under the table is that then there is no fiscal record of you being there. So if you get hurt or something, or fired and need unemployment or something, the records aren't there. But for most <$10 jobs out there, chances are it isn't too dangerous and no one should really care. (I read about someone who was a bouncer at a night club and was being paid under the table, he got hurt wile working and the club bailed on him. No medical or anything)