I had to have British Gas out once (in the days before Transco)when I thought I smelt gas, the bloke who came also thought it was gas, but it turned out to be coming from next door where an Asian family lived and was a cooking smell.

There's certainly one spice called asafoetida that really pongs as I remember buying some and everyone at work was commenting on the smell even thought it was inside my rucsack inside two plastic bags!