its what people who think they’re clever use as a word for people who are autistic. the “joke” is that autistic sounds like artistic, thus calling them painters like a coward.
Man that is some reaching.
Painters breath fumes all day, not that they are all that dangerous or anything, but leads to stereotypes. It’s also an inside joke among constructions workers, there is a “hierarchy” of trades and the painters are near the bottom, therefor the butt of most jokes.
Painters are also notorious for using drugs, in particular weed.
The stereotype exists for all the “wet” trades, plasterers etc, but painters get it the worst.