Nothing wrong with learning. Sadly, it's fairly common, with DSBM or something like that used to denote the nazi black metal artists. Outside of black metal it's generally less common, but last I heard the Epica vocalist really hates black people. Sabaton doesn't look too pretty either, being pro-Isreal and singing songs on nazi commanders and templars and shit. Don't let that stop you from being a metalhead though. There's good-hearted bands and good-hearted metalheads out there.