That's pretty much the misunderstood trope. Good is evil, evil has a reason to be evil, and all that.
I also don't see how whitewashing evil deities would serve anyone, or make sense. Bhaal is the god of murder, Shar is the goddess of darkness and loss, Bane is the god of tyranny. People who follow them don't believe in nicety, kittens and rainbows. They believe in murder, darkness, and tyranny, only to them those are good things.
Obviously Shadowheart should hype that shit, same for drows and Lolth, it would make no sense if they didn't, but regular people being chill with axe-murderers, ritualistic violence and all that for the sake of -- what? your character doesn't follow Asmodeus because he's nice -- makes just as much sense.
