One attraction of transportation cycling is the exposure to smells... more so than if you're traversing the countryside in your sealed-off, climate-controlled auto pod.
It's not all good. I don't care much for the stench of diesel exhaust... or gas exhaust, for that matter. But it's the price I must pay, so my fellow road goers can enjoy the freedom and satisfaction that can only be had by internal combustion, particularly in a huge diesel-powered pick-um up truck.
But a lot of it is just fine. Making me smell steaks grilling, or slow-cook smoke barbecue... that's downright cruel and unusual unless I'm invited!
Riding through the "country" - you know, rural America where agriculture takes place - will expose the rider to some of the best smells on the planet (spearmint fields, freshly-cut alfalfa), and some of the worst (feedlots, silage). (On the bright side, exposure to feedlot-smell is likely not hazardous to your health, like exposure to exhaust.)
For a couple glorious weeks every year, in mid-June, riders in the Boise area get to enjoy the fragrance of linden trees in bloom. The smell is reminiscent of orange blossoms, which I got familiar with when visiting relatives in the San Diego area. We are fortunate to have 3 big lindens on the west side of our house, which bless us with good shade all summer, and glorious aroma for a couple weeks, around this time every year. (The trees are rather "messy" - they throw pollen and sticky pods after they bloom, and lots of leaves 6 months later... but it's worth it.)
I've got to believe it's what Heaven smells like. Particularly if you combine it with a juicy ribeye on the grill.