I can think of all kinds of examples of memorable smells that I have encountered.
When I was in the army, my bunk mate would have these amazing wet dreams. They didn't always wake me up, but in the morning when he got out of his bunk, the smell of cum was really powerful. And yes, he was super hot!
When I was working in landscaping, this one really humpy guy would go home and fuck his girlfriend during lunch. For the rest of the afternoon, he would smell like sweat, and cum and pussy... then I would go home and jack off thinking about him.
sometimes at a group sex party the smell of saliva can be really strong.
and lets not forget about good old fashioned arm pit stank... When in San Francisco, I go to my favorite bar which just happens to be a favorite hang out for a lot of the porn stars from Treasure Island Media... As soon as I walk in, I can smell these guys and their beautiful body odor. I just sit near by and sniff it all in.
My first partner told me that he pursued me because he got turned on by my body odor.
I love smells. I really don't know how I would feel about sex if the smell was somehow taken away.