The biggest thing for me is to always make it clear you expect them to have a clear title in hand. That means it clearly states there are no liens on the bike. Even if they had a loan and paid it off and claim to have a notice of lien release, I would still have them send it in to their DOT and get a truly clear title. Up here in WI I've heard of a few people making fake lien releases as they are usually just an official looking bank letter and then the new buyer getting screwed. Also, I wouldn't take cash, I would get a cashier's check made out to the person's name and make sure that name lines up with the name on the title. I guess I would be a little overly paranoid when talking about something that costs as much as a C14.
As for the bike itself, if you are meeting at the seller's house ask them to not use the bike the day you come to see it. See if it starts properly cold. If you don't trust your own expertise, try to find a friend to come with or call around and see if there is a local bike dealer you could pay an hour of labor to go over the bike. Again, I may sound way over cautious, but I'd rather pay a little then get stuck with a $7K+ bike that doesn't work.