This should be a conversation starter!

OK, you don't like him, he smokes, he's a shoddy worker and you wouldn't employ him BUT you're not employing him. The best you can do is report back to the employers/house owners and let them sort out what they do about him and whether they withhold some money because of the shoddy work.

A lot of tradespeople smoke but I've never seen one smoke inside! Most smokers are conscience of the fact that non-smokers don't want smoke inside their home. I think it says a lot about this fella's character and attitude to work, especially since painters work around a lot of solvents which you are absolutely not supposed to smoke near.

Since your home is temporarily the painter's workplace, surely he is required not to smoke there.