Guilty Pleasure games, huh? I don't know if these are considered terrible games, but here's some that come to mind.
Sonic R - always thought it looked cool in stores, but never had a Saturn. I got it for PC years later in a Sonic bundle, and despite everything wrong with it, I think I really just enjoy the atmosphere and laid back feel that reminds me of the late 90's. It also kind of marks the end of an era to me - one of the final classic Sonic games. Plus I was hell-bent on unlocking everything.
Star Fox Adventures - Yeah, it would have been better as "Dinosaur Planet", rather than shoehorning in Star Fox, but I really liked this one. Again, the music, the atmosphere, the adventure. My only real gripe is once you beat the final boss, it doesn't allow you to return to the planet and get things you missed, so you have to start a new file.