This is just me personally, not a general comment on right or wrong.

In addition to good english, plot, and character development, I can't enjoy a bdsm story with a victim, unless the victim did something to deserve the punishment.

I didn't come in with this as a set attitude, it crept up on me. When I read excellent stories of sadism, I lose interest. Make the exact same things happen, but make it a revenge story, and I can read it through happily. Hating myself at some points, perhaps, but still enjoying the story.

This eliminates a surprising number of domination stories for me. Innocent victim = not interested.