I agree this is a DIFFICULT topic to talk about/solve -- as one man's vibration might be another's soothing back rub! LOL
The vibration I'm talking about is definitely more than you could sell a new car with (and enough so that I can comfortably classify it as an "issue"). It's also enough that it would drive me toward a solution (or sale if never corrected). It's one that creates cabin resonance at hwy speed where passengers are annoyed (mainly in the back seat). But, it's definitely coming from the motor (since it is present when parked).
After reading Jerry's response, I tend to think this is a motor mount issue. Plus, the current owner had the belt removed, checked for balancer play, and if the vibration still existed w/o the belt. It does and there's no play.
That pretty much means it's the mounts (or the motor). When/if I can confirm the mounts, I'd like to purchase the VX in question.
The downside is the same shop said they did not see a problem with the mounts either. But that's probably harder for the average mom/pop wrench-turning shop to determine. It's one of those areas where a (dealership that's seen more specimens) might better diagnose. OTOH, lots of dealers have seen very few of these!