Remove the polish, and what people are really saying is that if you buy at Streamside you should have your head examined.
The place has more bad history than Carter has pills, dating back to the pre-Marriott, Steadmside at Vail era.
While one can not refute the reasons to want to vacation in Vail, if you want a Marriott timeshare in a ski town, I'd consider one of the lock-off resorts in Park City, UT or Lake Tahoe, or a non-lock-off one bedroom villa at Mountain Valley Lodge in Breckenridge. The problem with Mountain Valley Lodge is that the largest villa there is a large, one-bedroom villa, and although it sleeps 6, II treats it as a one bedroom, so when you trade into a lock-off resort, all you'll ordinarily get is a one bedroom. II counts bedrooms and not beds for exchange purposes.