Hate Dumb: Most of this stems from people who think Cee Lo's an attention whore, not only because of his outrageous fashion sense that rivals Lady Gaga and Nicki Minaj, but also from people who think he's a gimmicky artist famous only for a profanity laced track title, and the catchy pop song "Crazy", despite Cee Lo working in the music industry for at least a decade (and not just as a producer/singer, but song writer). Some detractors noted that Cee Lo co-wrote for the Pussycat Dolls single "Don't cha", increasing the hate. Then the 2012 New Years Day flub happened, and the outcries of Cee Lo being a hack increased ten fold (see Internet Backlash).
I Am Not Shazam: There are a good number of people who thought "Gnarls Barkley" was his name.
Internet Backlash: Of all the things Cee Lo could have said to spark off this reaction, it was changing a couple of lyrics from the John Lennon song "Imagine" when singing the song during 2012 New Years Day. Although not all John Lennon fans were upset at Cee Lo, the rest of them gave him the kind of disapproval usually reserved for Justin Bieber. Ouch.
Misaimed Fandom: A rare positive example. According to a JET magazine interview, Cee Lo said the main reason he wrote "Fuck You" was to get forced out of his contract with Atlantic Records, since he felt that the company constrained his sense of creativity. Ironically enough, despite the song primarily designed as a Take That to Atlantic, the company loved the single and enthusiastically advertised the song afterward, along with the album "The Ladykiller". That's not to say Cee Lo wasn't grateful for the odd change of heart.
Sequel Displacement: Despite Cee Lo's connections to Goodie Mob and his Gnarles Barkley material, a surprising number of listeners (mostly older R&B fans) think he's a new artist, and that The Ladykiller was his first album ever, rather than his first full fledged R&B album.
Wangst: Parodied with the Gnarles Barkley single Whatever.