They'll lose a few hundred quid. Nothing really compared to the couple I met who wouldn't view any properties without their "special friend" coming along to advise them. They trusted him completely, and he sorted out a purchase without any agent or lawyer. They trusted him enough to pay £18,000 more than it was displayed for a property than it was in just about every estate agency window in the region.
Like I said, you have to let the gullible ones go. Even if you went to them and told them face to face, they probably wouldn't believe you and would hate you forever. I used to feel some sort of sorrow for them but sorry, it makes me p*** myself laughing these days. Especially when they email me for advice because it's all gone wrong.