I was messaged by a local business owner, asking if I'd be interested in putting his product in my listing photos, mentioning the business in the listing, and also in my "welcome to the apartment" notes for visitors.
Next time I was in his shop I told him I really don't rent the place out enough for it to be worthwhile, but asked him how the response from other people he messaged was. He said one woman was really angry in her message back, and a few others took him up on the offer. To be honest the ROI for him wouldn't be great, especially given many of the customers from AirBnB won't be returning.
If it is against AirBnB's terms and they take issue with it I can only imagine the irony-laden field day the media would have.