How come you never hear the phrase “I’m not racist but …” apart from when it suffixes something racist? To my knowledge, nobody has ever said “I’m not racist, but did you know that bauxite is the most plentiful source of aluminium in the world?”
Then again, you never hear anyone say
“I’m not hungry, but I’m just going to eat this sandwich”
“I’m not interested, but I’m going to listen to what you say anyway”
“I’m not medically qualified, but I fancy having a go at heart surgery”
Hmm. Needs a bit of work, that one.