I think they do. Take for instance, a NYC subway stop after it has rained. Or the Atlantic Ocean vs. the Pacific Ocean. Or prairie grass in the summertime.
What's weird to me about smells is that (for me at least) it depends so much on our other senses. Smelling the same flower when it is -20 below and when it is 80 degrees doesn't feel the same. Or at night time certain smells seem more intense since my nose works harder.
Am I talking crazy here?