Does everything we know in our physical world have a scent? It seems like many things in the plant and animal kingdom are driven by scent. What animal has the best sense of smell? There are certainly things dogs can smell that we can’t. Are there manmade substances that have no scent?
Air doesn’t smell, because you’ve never (or extremely rarely) not smelled it. I’d imagine a diamond wouldn’t smell.
Since it’s probably virtually impossible to have pure air (in an uncontrolled environment), there’s probably always odors “in” the air. But whether “pure” air has an odor, I don’t know. I wonder if glass has an odor to it?
I think by smell you mean something at emits molecules into the air that can be detected because their conformation allows them to bind to specific receptors in our noses and stimulates an electrical response that we recognize as smell. Well, probably just about everything sends molecules into the air, but not all of which are detectable by our noses. I would say yes, everything has a smell.
Certainly not… many gasses are odorless, for one. I’m sure there are many solids and liquids that emit no particles, and therefore have no smell. Diamonds are a good example.
I also find smell to be a fascinating topic.
I read a very old (but I suppose accurate) encyclopedia article on line that said that we cannot smell things below a certain molecular weight. For example, methanol has virtually no odor, whereas ethanol (a heavier molecule) does.
We think of salt as being odorless, but on a salt industry website, it said that sodium-deprived cows went straight for salt-water tubs, indicating that they could indeed smell it.
There may be other conditions as well. I doubt that pure water could ever have a smell.
Hence, just because something has no smell to homo sapiens does not mean that it has no smell to any species. But some substances might have no smell to any species.