I just checked E-Bay, and here's what I found, without even much of a search:
Wilderness Lodge - 3 listings. 1 was by smw, and didn't have any dates assigned to it. 1 was by boardwalkmagic, for an October reservation. Both of these sellers had lots of comments about previous DVC trips that had been sold. The 3rd one was for a "sold out" holiday reservation in December. However, it doesn't appear that this seller has any previous comments about DVC trips.
Old Key West - 3 listings. 1 was by vacation4u, no specific dates. 1 was by smw, no specific dates. 1 was by boardwalkmagic for a sold-out Halloween week.
Beach Club Villas - 2 listings. 1 was by smw, no specific dates. 1 was by disdvcer for a "sold-out" food & wine date, and a statement that there was an additional week available also.
Boardwalk - 6 listings. 1 was by disdvcer for a "sold-out" Halloween week, with comments that 2 other additional weeks were available. 1 by smw, for a standard view, no specific dates. 1 by smw, not standard view, no specific dates. 1 by boardwalkmagic for the 1st week of October. 1 by jidivine for a standard view in December. 1 by jidivine for another standard view with a different December week.
Saratoga Springs - 3 listings. 1 by boardwalkmagic for a "sold-out" New Years week. 1 by smw, no specific dates. 1 was for Labor Day week, but this seller doesn't have any comments about previous DVC trips that were purchased.
If a listing had been removed, it was probably because it was purchased, or the time had expired on it. I don't see any evidence of a crack down by Disney on the E-Bay listings.