The first two years of the 800 small block engine were horrible. Polaris recalled every one of them to replace the head, cylinders, and reflash the ECU. They were burning up big time. Polaris worked at fixes, the after-market worked at fixes, but it took years before Polaris finally had an 800 engine that was a little dependable. Polaris lost a lot of riders over those 800 issues. By 2012, it was better and by 2014 the 800 was a pretty good choice, although not as powerful as Cat or Doo.
So some guys with Dragons are trying to upgrade to a newer chassis with an engine with less problems. And some are trying to get rid of a lemon. Steve suggested making sure updates were done. I would add to that, if they were done, how many miles since the update? Any issues since then?
You pays your money, you takes your chances