-Women wearing so much perfume that it makes you gag when things start getting sweaty.
This is a trail pet peeve of mine. Out hiking there was a woman in the group ahead of us who was so drenched in fragrance that my allergies started going berserker. We were at elevation so the breathing thing was going to be a challenge anyway, but I didn't want to start out compromised. And, they wouldn't let us pass them. Actually, we did pass but then they started cutting switchbacks and got ahead of us again. Blarg.
I cannot deal with overly scented anything (including people)!