Was there more than just 'paint' in that spray booth?(spoilers).
Spoilers......
When Kotto is locked in the paint booth, he DOES have on his mask and protective gear, doesn't he?? If so....it would seem unlikely that mere "paint" would kill him like that.(Unless the mask had been "worked on". ) It never said so...but most likely a bit more than "paint" was sprayed in there. Perhaps a bit of chlorine gas or such, with the paint.