2. Picaridin-based repellents ... actually attract gnats.
Really?
In my experience, it repels black flies (bigger gnats), while DEET basically puts the dinner bell around my neck for the little monsters. And I'm allergic to them, the anticoagulin or whatever it is they inject is like poison ivy for most other people.
It also has one major advantage- it doesn't eat nylon and other plastics.