Kinks - Soap Opera. I have a lot of affection for this, even though some of the dialogue sections are pretty bad. There's at least five very good songs on it, and it is genuinely funny at times.
Fleetwood Mac - Time. Pretty bad, but as they mention in the writeup, McVie's "I Do" is a good song.
Liz Phair - Liz Phair. I felt similarly to RS once, but this album has grown on me a lot and now I think it's genuinely good, even if some of the lyrics are fairly silly. I know this is the highest-profile of her "bad" albums but it's much better than Somebody's Miracle and it's even less cringey than Funstyle, both of which would have been more reasonable inclusions.
Joni Mitchell - Dog Eat Dog. Can't really argue with this one, it's definitely not very good, but I think it's probably better than some of her '90s albums, which are pretty unmemorable, or her '00s orchestral albums on which her voice is gone. But for me her worst album is probably Mingus, especially considering all the talent behind it - it just doesn't work at all.
Madonna - American Life. Yeah, this sucks - far worse than any of her other albums. Good pick!
George Harrison - Gone Troppo. I don't remember this at all, but I'm unconvinced it's actually horrible.
Velvet Underground - Squeeze. I've played this out of curiosity, and similarly, it's not horrible, just boring.