I would still Double check "digit for digit" the VIN number given against the frame when you go in person to purchase. It only takes one incorrect digit!!!
I personally will not purchase without title. For reasons others have stated above "liens, Stolen". I don't care how good a deal it is. There is no reason not to have the Title for a bike these days (if its older than late 90's MAYBE). I've heard all types of excuses, and stories. But at the end of the day I think you are contributing to stolen bikes. Directly or not, your contributing to bikes being stolen from out of peoples garages or trailers, or from the lenders, its all the same!
Lately it seems like there are more bikes for sale without titles than with??? You get caught holding the bag and you are guilty just the same. And you will be out of your Cash and and the Bike.
If it is legit then they should be able to provide or acquire the title!!!
If you bike was stolen and sold, would you feel the person who bought it from the thief was any less responsible?