I used to go to a school in the rich part of town and the entire campus smelled like perfume from all the girls wearing it.
I've never noticed a bad odor from a girl though.
I've noticed that boys generally smell like sand until they're about 14, at which point, if they don't use deoderant and bathe often enough, they smell sour.
I've also noticed a lot of arab men smell like hummus, which doesn't really bother me unless they smell like sour hummus.
My mother used to complain that Asians smelled "sweet", and I hear from a lot of Asians in Asian countries that Caucasians supposedly smell "bad".
They are both actually on to something because there are two types of sweat glands, apocrine and eccrine. Apocrine glands tend to make you smell, well...like hummus or chicken, but also secret phermones responsible for sexual attraction. Eccrine glands secrete sweat that doesn't have much of a scent.
Caucasians and Arabs have far more aporcine glands than Asians. This is probably why there is that Asian man, caucasian woman divide...women are sensitive to phermones, or lack thereof (that's right Asian guys, it's not how you look, you just don't smell bad enough!)
It's also probably why my mom thinks Asians smell sweet...because they don't smell like chicken or hummus.