Hi vintagepbs,
We were receiving a number of reports up until the beginning of this month that Auction Sniper was returning "Could Not Find Item" errors upon trying to add snipes for items listed in eBay's "Mature Audiences" categories, but that issue seems to have cleared up since. This seemed to be occurring due to some changes eBay was experimenting with but apparently they have decided to roll back those changes.
I'm not aware of any current issues specifically affecting snipes placed on items in eBay's "Mature Audiences" categories, so I'm skeptical to confirm that the failure of your snipe on item # 260169864395 had anything to do with the category in which it was listed. If you file a support request using the appropriate link at the bottom of our help page,
http://www.auctionsniper.com/help.aspx we'll be happy to take a closer look and discuss the possibility of offering you a couple free snipe credits.
-Mike