After mentioning that plenty of people seem to miss the 'No dogs' in the advert he texted me to say he has a 9yr old Springer, then sent me a photo of said spaniel. I said that it looked very much like a dog to me. He then said he'd like a long tenancy and that it was soon going to be illegal to refuse to rent to someone because they have a dog.
Relying on the fact that I'd explained 'no dogs' I elected not to discuss it further but he kept on at me, sending me a screenshot of the bottom of the Rightmove advert which said 'pets considered'. I don't know what he thought he was trying to achieve but I screenshotted the full ad on Rightmove, highlighted the 'No dogs, cats considered' wording and sent that back to him, whereupon he replied saying that it doesn't say that on Rightmove

So I blocked him. Clearly not somebody who would be a good tenant in any case, but WTF did he think he was trying to achieve?