@Randomguy01
Based on my expert knowledge on the subject of why people hate mangas. We have the following key points:
1. Plot - People will always hate it no matter what it consists of
2. Sex - People hate graphic sex in manga, they prefer it to be segregated to hentai or to be vague as possible
3. Censored Sex - The people who do like graphic sex, hate censors, since it's basically cock blocking them
4. Slaves - No matter how you spin it, if you got slaves you got bad ratings
These are some of the main reasons, I'm sure I am missing some.
But also, if you see smut without gore, a good rule of thumb here is, the lower the rating the closer to hentai it is.
If you do see gore, welllllllllllllllllllllll it's probably getting down voted to like a 6 because people, in general, really, really hate abuse or rape or anything near that, but it stays near a 6 bc you have those people who will defend anything, and I mean anything.