ummm, this question is less about what makes 'um smell bad but how long you can make 'um smell bad....

Ya' gotta go fir the like the defroster ventin' because it's gonna be hardest to all to clean out....

So here's my advice... Get you a can of sardines and jus' drop 'um, opne by one, down the defroster vents which are up on the dash board and send hot air to the windshield...

(Oh, Bobert... This borders on terrorism...)

Nevermind, ignore my suggestion...

...unless this is down and dirty revenge, then go fir the sardines in the defroster vents...

(Caution note: This may "total" that car so be prepared to answwer questions that may be asked of you by the other parties insurance company...)

Bobert