The plastic shelf pans in my CN are getting pretty grody, too :/ When the weather gets a bit warmer and I have more energy (I'm sick currently and while I'm almost done my antibiotics, they're making me feel crappy and lifeless too, ugh x.x) I'm gonna have to pull them out and give them a good scrubbing..... He doesn't chew them so I don't have them covered, but I don't want to spring for metal shelf pans since when I have the money I plan to just replace both of the original shelves completely with wooden ones (the main bottom pans have already been replaced with metal ones at this point so they aren't an issue). Its good to know I can use a little bit of bleach if need be. If its crusted on, maybe a thin paste of baking soda and water and a good ol' fashioned scrubbing would help?