AC smells bad every summer, like stinky feet. I spray some ac cleaner in it with the ac on full blast, and it takes care of the odor.

I had a scheduled maintenance at 9800 mile and reported the problem to the service adviser. They went ahead and replaced the air filter to see if that would illuminate the odor, but it came back again. My suspicion is that there must be moisture trapped along the ducts or the evaporator unit. Sometimes I noticed water droplets flying out from the vents but didn't give much thought then.