There is in show biz something known as "a bad laugh". That's the laugh you don't want to get, because it indicates not amusement but incredulity, nervousness or disapproval. John Waters' "A Dirty Shame" is the only comedy I can think of that gets more bad laughs than good ones...We go to a Waters film expecting bad taste, but we also expect to laugh, and "A Dirty Shame" is monotonous, repetitive and sometimes wildly wrong in what it hopes is funny.