Nowadays, there are many fake tokens, so it is better if the seller does some research to determine whether it is legit or not. By the way, this is the first time I've heard of someone buying a house with tokens, and I don't think scammers can easily buy houses given the amount of paperwork that needs to be completed.
I think it will be insane to accept fake tokens as payment not unless the seller has zero knowledge about cryptocurrency. If that's the case, he should have do a research about the coin first before accepting it. Scammers are everywhere and we can't get rid of them easily but the best thing to do to avoid being scammed is to be skeptical especially if there's money or property involved.