Hi Jim,
There are a few reasons that an eBay link may stay up, but the most obvious is that we just flat out miss things from time to time. While Dave, Matthew, Jeff and I certainly try to catch everything, it's not a perfect system and things will slip by the goalie from time to time.
For the most part, this board has been very good about self-policing over the years and if there's ever a post you see that you feel is inppropriate for any reason, feel free to bring it to the attention of any Admin by either emailing them directly or through the Reporting Forums.