I clean my plastic kitchen trash can every week or so by bleaching it and sitting it outside on the porch to air dry.  Often onion peels make my trash can smell rather strong and the smell seems to absorb into the trash can even after the trash has been taken out.

So, between times of bleaching or scrubbing clean, I put a dryer sheet in the bottom of the can before adding the new trash bag.  I buy 50 Breezy “fresh linen” dryer sheets for a buck at the Dollar Tree.