I'm definitely open to replacing the tubs--I don't have so many snakes at this point that it would be prohibitively expensive, and it would be worth it to know that my snakes (and myself) remain healthy. However, I don't think it's the tubs--I think it's actually in the wood/melamine. You wouldn't believe how nasty it was--it's designed as most are, so the tubs don't need lids. It looks like this jerk kept his animals in filthy tubs for months--the snakes would wind up wallowing in their own accumulated filth, smearing it all over the shelves of the rack.

I scrubbed the rack and shelves down with Lysol, then hot soapy water. The tubs were soaked and scrubbed down with bleach and hot soapy water. Both the tubs and the racks were left to air for the week between picking up/cleaning and plugging them in yesterday. Most of the tubs actually cleaned up well (those that didn't were trashed)....I think the odor (and potential microbes) is in the actual wood/melamine. If I had realized how bad they were, I wouldn't have bought them. Unfortunately, they were in a dark garage when I went to look at them, and I didn't realize the degree to which they'd been neglected until I got them home.