Nothing someone says before the word "but" really counts.

The remark points to how “but” often functions as a rhetorical eraser: it signals a reversal or qualification that undercuts whatever came before. In everyday speech, people may preface a harsh judgment or refusal with softening language (“I’m not racist, but…,” “I like your work, but…”), and the clause after “but” typically reveals the speaker’s real priority. Read this way, the quote is a caution about listening for the operative claim rather than the polite preamble, and about recognizing how disclaimers can be used to evade responsibility for what follows.