The smell of chocolate chip cookies or cookie dough makes me SO sick to my stomach! I can't stand it! Haven't eaten one since 7th grade, unless it is almost unrecognizably burnt!! (Yes, I did have a bad experience involving mass quantities of cookie dough...)
My wife just reminded me of another sickening smell (for those of you who live in a part of the country where you need to heat your home with a furnace).
The smell when you first turn on your furnace in the autumn. All the accumulated dust on the heat exchanger makes an awful smell until it burns off.
Seafood. Ever since I dissected a shark 2 years ago in bio, that is all that that smell reminds me of. I'm not real wild about the smell of the embalming fluids the companies use for those animals either. In fact I was dangerously close to getting sick dissecting a fetal pig today because of that smell.