Naomi's not romantically linked, but still jerking Cas around, including making him kill hunders of Dean copies. I stay away from SPN fandom as much as possible, so I'm not actually sure if Naomi's hated. Wouldn't surprise me.

Jo both had feelings for Dean, and he admitted he had feelings for her he wouldn't act on. And, to be fair, even Kripke said she was a flawed character.