I'd just like to say to that that I've never seen an add where someone is selling stuff that they don't say in the description what it is. Even if they can change the title, with what I'm suggesting you couldn't edit the main content of the thread, so even if you changed the title the main bulk of your post would contradict it.
Edit: I'm not saying it couldn't be done, but you would have to be a very trusting person to buy from someone that didn't have a description other than their title.