I suspect that 'right' versus 'wrong' types of slavefic would be entirely a matter of personal taste. My right would, without a doubt, be quite wrong for a lot of other people. It's one reason that I don't tend to browse the tag on AO3-- I just don't have a good way to filter what I'm interested in from what I'm not, and what I'm not seems (isn't it always the way?) to be more popular among readers and writers there.