A change in olfactory seasons

I've been told that autumn's first killing frost is when bird dogs start getting serious about hunting.  Up until that time, according to legend, there are too many distractions for a nose with superpowers to sift the good stuff out reliably.  There's a brief period right after that first hard frost where all the vegetation's dying, which I imagine is something like the overpowering stench of sargassum washed up onshore in the Keys, and they struggle a bit until that passes.  Fortunately it doesn't have the staying power of sargassum and in a few days the dogs are in business.  In fall and winter and a dog's nose has one focus:  game.

Spring rolls around, however, and another legend has it that gamebirds stop giving off much scent, something to do with protection during the nesting season.  An idle nose is the Scent Devil's playground.  Bugs and snakes and frogs and the other critters that hole up in the winter come out to play.  Weeds and flowers and seeds hang in the air.  And food on the table, my oh my, how the interest in that rises through no apparent coincidence.  The rest of the earth comes back to life.  Even a lowly sniffer like mine gets drunk on the smell of honeysuckle and lilac.

A wet, pink nose is born again with a new purpose, millions of new smells to sample, savor and catalog.  Moving from one end of the yard to the other can take an hour or more in what must be akin to wandering the aisles of a really, really fine market and being allowed to taste every single thing on the shelf.  These must be the rewards for having to sleep on the floor and eat the same thing at every meal.

What I can't figure out (among other things) is how a nose that sensitive isn't completely pillaged by pollen.