For example does pic related count as a fucked up ship? Sure they hate and live to kill each other, but when you think of the actual dynamic it doesn't even feel that fucked.
In fanworks they are mostly depicted(and I agree to an extent) in a low trust give-and-take relationship that works decently on pre-canon, that gives them a way to vent and ease the loneliness but still allowing for good tension and sense of danger.
I could even argue that in the Souls universe having such a strong emotion or desire such as hate can prevent one from hollowing and from that perspective it can even be seen as a good thing, as some sort of coping mechanism to retain some semblance of humanity, even if so seemingly unhealthy at first glance.
It is very interesting to talk about these things, what qualifies as a fucked ship to you?
To me the appeal of a fucked ship is more in the relationship dynamic than if they have any characteristic that makes it "morally wrong".
For me for, example
>>3235366 KaraIchi aside from the incest is actually a good relationship that I wouldn't consider fucked with other characters.
I think it should also be noted that, like most things, this is better measured as a spectrum of unhealthiness and not as black and white thing, this also helps preventing this turning into a "post every incest/shota/age gap ship" thread.