X-perts on the Genesis was atrocious, and a defilement of the perfectly good Eternal Champions, to boot. I must admit I found something perversely enjoyable about it, though...
I'd mention Virtual Hydlide (Saturn), but it's one of the "best worst" sort of games. Here's a review of it that does a pretty good job of describing it's retard majesty - "http://www.gamefaqs.com/console/saturn/review/R36554.html"
My pet turd of the gaming lineup, though, has got to be "WURM: Journey to the Center of the Earth" on the NES. Now that's something I truly love to hate.