That is a shitty thing to do. I'm having a similar experience with my recently purchased 990, although not nearly as bad. It is my fault for not being diligent in my inspection of the bike and more direct in my questions before buying. Had I known about the lack of maintenance, the extent of needed repairs and the real possibility of a complete engine rebuild I would have offered $2k less.
If the previous owner had been forthcoming about the bike's problems, I would have known the guy to be honest and taken my chances on the deal. Again, it's my fault for not being thorough, but that doesn't excuse his deception and his willingness to let me drive off with a time bomb.
Too bad, now he's just another guy I can't trust.