i can't stand them when they're fresh. after they've been in there awhile they just kind of linger in the air. when they're in the outlet and fresh, it can get pretty nauseating if you're in a closed room for a long time.
when I was a kid, I took one of those type of things and i popped the pack open. The gel got on the wall, and it was so strong, everyone in the house got really ill.
Well most of them are gross, hawaiian breeze and apple cin are the only two I can stand. The wild berry one or something made my room smell like beer and the linen one made my room smell like toilet paper.