Can plastic hold odour?
I'm wondering this because when I take the litterbox out of the closet to clean it completely, the closet smells totally normal and clean. But even when I put the clean litterbox back in, with clean litter in it that my cats haven't touched, a smell comes back into the closet. Could it be because I've had the litterbox for 2 years? Should I get a new one? I clean it completely every 2 weeks, hot water and soap, and let it air dry.