Some state laws do not restrict commercial usage [0] amd AFAIK, there is nothing in the federal FOIA law that prevents using information for marketing or other commercial purposes. That wasn't my point, though. The parent commenter talks about the potential danger of phishers using public data as being "against the spirit of FOI". Yes, I agree that using FOI to find info that facilitates a crime is not FOI's intended usecase. But the potential drawback has not been determined by legislators to outweigh all the potential benefits of transparency.
It is done but not legal and hard to prove.