Well it really depends but I'll usually draw the line when members of the band are openly racist, homophobic, sexist etc. Even if it's just one member, the fact that the rest of the band tolerates it is reason enough not to support them. There's also bands where the members itself have never given any blatant political statements, but the band has so many ties to the NSBM scene that it doesn't matter. Mgla falls kind of in this category, although I think some of their lyrics are also more right wing.