I bought a bike with a lien on it once, kind of. Here's how we made it work:
I went to the person's house, saw the bike, saw this person was very much settled in there (didn't look like a renter, wasn't in a building, etc).
I left a very small deposit (few hundred bucks) to show good faith.
I left and the seller went to the bank to wire the money to pay off the bike.
Two days later we called the finance company, from my cell phone, from the number I googled, put them on speaker phone, and together we went through the situation with the customer service lady who verified with the VIN# and the loan number that the loan was paid off and they already submitted for the lien to come off the title. I also had her confirm that once the loan was closed it could not be re-opened again.
Then I gave him the rest of the money and left with my bike.
So, I get why everyone else is saying run away, however, I'm a firm believer in this:
If everyone else is running away from this Vespa, which based on the forum, might be the case, that's a great opportunity for you to swoop in for a really good deal,
IF you find it reasonable to trust this person to not disappear on you and pay off the remainder, and
IF you take precautions like using your own phone, calling the number for the finance company you looked up yourself, and verifying everything yourself.
I got my old Suzuki Boulevard for $5,000. Three years and 5,000 km earlier it had cost the guy $10,000. Nobody wanted the bike with the lien on it, but I did. I rode it for several years, loved that bike, and when I sold it I managed to make a profit on that bike and put it towards my V-Rod.
Be greedy when others are fearful.