Based on multiple articles and threads on this over the years, real bloom is likely byproducts of the bacteria that feed on compounds in the tobacco that make tobacco smoke harsh. It's not sugar, and it doesn't add flavor. It's just an indicator of how much bacterial processing has occurred. It is crystalline, and should sparkle in the right light under magnification.
That said, some toppings, if applied heavy enough, can also precipitate out of solution as the tobacco dries. This also leads to a crystalline deposit on the tobacco. This will show up on young tobacco, and doesn't require aging, just drying.