“You called Senator Sanders everything but an ignorant slut,” Senator Kennedy said.
Does "everything but an ignorant slut" mean "not an ignorant slut"?
No. But = except.
OED
C. conj. I. In a simple sentence, introducing a word, phrase, or (rarely) a clause which is excepted from the general statement. With the exception of, apart from, except, save.
2013 Arab Stud. Jrnl. 21 96 My heartfelt thanks go to the following readers for their helpful engagement with this essay, however, none but I bear responsibility for its frailties.
1934 Cairns Post (Austral.) 29 May 4/5 This gangster's scheme will benefit nobody but the silver producers.
2003 Daily Mirror 1 Apr. 47/1 None but an eccentric few give a hoot.