I don't really mind the smell of rotting potatoes. When I was little my grandpa grew potatoes for market and they were stored in giant heaps in a barn, so there were always a few that rotted. It was an earthy, musty smell. Maybe getting used to it at a young age helped.
Smells that truly offend me are perfumes, marzipan and what ever came out of my tooth when the dentist fixed an abscess I had. Rank.