His productions discography is horrible besides Hybrid Theory. Good Charlotte? Hollywood Undead? Yuck.
Eh, Good Charlotte is just OK for me. They have a few good songs, like The River. And Don Gilmore is the bastard who ruined Hollywood Undead huh? Figures as much, I really enjoyed them before they became part of the mainstream. I would also like to point out that Don Gilmore ALSO fucked up Bullet For My Valentine's Fever, which is a shame, since Bullet For My Valentine is one my favorite bands of all time.
He also ruined Lacuna Coil. Their last record is poppish crap. But you can't blame all on him though, it's not like band can't choose their producers.