I always assume if its a good deal and no title its probabally stollen. If you ever end up in the unfortunate situation of being the owner of a bike with no title....I just say pass the buck and move it along. My bike came with the slip, no issues changing it over even with the fact the guy who sold it to me was never registered to the ownership only the previous owner before him.
The P.O. never registered because he could never get it running anyway. Win for me!