It's either. Love to Hate is a character who offers an old fashioned mustache twirling charm to being a bad guy, shouldn't quite reach Evil Is Cool but they are a satisfactory opponent to the hero. Hate Sink is a character so despicable that the audience is primed to cheer when they are finally defeated. One you want to stick around, the other you're excited for them to be killed off.
I initially thought you were talking about Nice Character, Mean Actor.
![[up]](https://static.tvtropes.org/pmwiki/pub/smiles/arrow_up.png "[up]"){kind=icon}
of course it doesn't have to involve actors - I was primarily referring to how the character is written.
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I don't think we have this concept. This is something pretty subjective- praising the character is actually praising how the character is written, while you could despise what it is they actually do, you can love how realistic they are or their impact on the plot as a whole. And that's not something covered by Love to Hate or Hate Sink, though these can overlap with this concept.
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About a character that the audience hates so much for their attitude and actions, that they're then praised as a good example of a "despicable character done right".
This may sound like a Trope Finder entry, but I think this is deeper than that - is this Love to Hate, or Hate Sink?
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