Here's my suggestions.

I too have vents in the floor. If the vents have a bend or curve near
the bottom where they go under the floor toward the furnace, you can
stick either a store-bought vent pad that's scented or just a lain pad.
I think they are sold to help catch allergens. This of course means
checking them regularly. I just gave up on having the vents screwed in.

I also took fine window screen, cut then large enough to not only fit
over the the vent opening, but large enough to form a well (to give the
vent blades a chance to move), placed them over the vent and then put
the vent back. This catches all sorts of things you don't want in the
vents.

As for the smell of mice... I have mice. I also have six useless
ferrets, one useless cat and three useless dachshunds. I am now
threatening to fire them all if they don't start catching the mice.
Anyway... I use a strong vinegar and water solution. I just wipe
down the surfaces.

anne

[Posted in FML 5590]