So I worked in the business as a SA for a couple of years, meaning i smelled many fragrances on many people, and my conclusions, which are just an opinion, are that
1. Yes, there is some skin chemistry involved, but it's not the way you think. It's more like ok 10% of the smell can vary from skin to skin and I didn't really even notice much. It's more the case that if you're someone with difficult/tricky skin, then everything will change 80% when it hits your skin. So yes, there's some variation on everyone, but not much, more like a few people who really make things smell different. Anything from skin acidity/pH, bacteria, previous fragrances from that morning, smoker+diet, even the relative factor of what else and how much else you've been smelling that day, and the fact that the whole department is filled, filled(!) with perfumed air. Also, some people are just lucky. My father holds and project scent beautifully, anything on his skin just lasts 8-10 hours at full volume. I suspect either he sprays too much (it's never too strong though, he's not 'cologne guy'), or sprays on his face (maybe that works?), or it's all the chest hair.
2. Yes, I can actually confirm from experience... light asian and whitey white skin tend to be the trickiest. They may turn fragrances sour or just suck it up. Mediteranean skin to Middle Eastern skin, and colored or black skin, definitely make fragrance just bloom. Darker skin absorbs, blends, and nicely projects out fragrance. Of course it's not always 100% true, just more often than not. To white noses, darker skin, including diet often also strongly stinks too, so it's all relative. And for fcks sake don't message me anything about racism or whatever.