The mealworms have no odor that I've detected. Their dry environment helps a lot in that regard, I think. The only moisture they get is some carrots or potato chunks. Just be sure they always have a piece or two in their bins.
I only use two bins now. I used to do three, but I didn't really see a need for a "middle" stage bin, so I did away with it. My "system" works like this:
In a fairly large bin, I have all my beetles and pupae, along with some larger worms.
Every few days - maybe once or twice a week - I take a large wire strainer and scoop up some of the bedding (I use wheat bran and quail/chicken feed "dust") from that bin and shake/sift it over the other bin that is for my feeder mealworms.
The strainer I use has mesh about the size of regular window screen, so it allows the smallest worms to fall through, as well as most of the eggs. This way most of the eggs will be hatching in the bin with the feeders, and can grow out there, but a few will remain with the breeders, so I don't have to worry that I'm depleting my future breeder stock.
Any mealworms I scoop up in the beetle bin that manage to grow too big to fall through my Strainer of Doom are deemed SAVED, and get to go back in the beetle bin to live out their happy little mealworm lives as breeders.
When I want to collect some worms to feed out, I use the same strainer in the feeder bin, shake/sift back into the feeder bin and whoever doesn't fall through the strainer gets fed to the critters.
It takes some time to get a set-up like mine established, but once they get through about two generations, they'll be producing a ton of worms. Just be patient with your first batch, and let them all grow out and turn into beetles.
