"Favorite bad albums": I love this game. I want to play, too.
Let's define terms first, though: "Bad" as in, I-know-this-is-horrible-but-it's-my-guilty-pleasure bad? Or as in this-is-actually-kinda-good-but-perhaps-underappreciated?
If the former, I think I'm going to have to go with Genesis' "Invisible Touch." What can I say? That it grabs right hold of my heart? Let's not go that far, but someone cue up that Tony Banks synth riff for me right now. And, while you're out, dig up that episode of "Magnum P.I." that had "Tonight Tonight Tonight" all over it. What other band could toss a prog-rock opus like "Domino" at you, and then sneak Top 40 creampuffs like "In Too Deep" and "Throwing It All Away" through the back door?
If the latter -- truthfully, I'm not sure this counts, but I'm sure someone out there will wince when he or she gets past this em dash -- I'll nominate Stevie Nicks' "This Wild Heart." (This is assuming that her first solo album, "Bella Donna," which I consider a straight-up good album, is still a critically reputable effort as well.)
Prince's chintzy little keyboard riff in "Stand Back" tickles me every time (here's the story on that collaboration, if you care to know). And "If Anyone Falls" -- more '80s synth! The kind not coveted today by vintage-analogue indie-rock connoisseurs!
I am not ashamed.