I left one of the mugs at the back of my hood last week, where I'd been using it to hold a dry-ice/acetone both to cool a reaction. Yesterday, I noticed that it had changed colour and gone ... reddish. It turns out that the atmosphere in my hood is sufficiently caustic that it had not only eaten away all the coating, but was merrily chewing away at the steel as well, rusting it to hell.
I'm torn between (a) I work with really cool shit! and (b) I breathe this every day.