Yeah, since TV Tropes has a Hate Sink Cleanup thread, I thought there should be one here too, since there may very well be invalid HS examples here and there on this site as well.

On that note, I actually have an example I'd like your opinion on whether it's valid: D.W. Read from Arthur. Yes, I know I was the one who proposed her as a HS in the first place, but if you look at the blog post in question, you will see that I myself had some doubts on her validity as an example due to the fact that, while she is an unsympathetic antagonist in episodes focusing on the show's titular character Arthur Read, the show does also give (or at least attempts to give) her a Sympathetic POV in her own focus episodes, whereas the HS entry (found on the show's character sheet) is simply "she does terrible thinks[sic] to Arthur, so it's clear she's not meant to be liked", even though her own focus episodes do give her more character depth than that, and the user who added the example did so without even addressing my uncertainties about her HS status first. Not to mention the fact that she is also listed under Unintentionally Unsympathetic on the show's YMMV page, which is mutually exclusive with Hate Sink for obvious reasons. The show also has Deliberately Bad Example characters designed to make her more sympathetic in specific instances in the forms of the Tibble twins and Cousin Cora (the latter of whom is a One-Shot Character).

But on the other hand, Marc Brown has fairly recently referred to D.W. as "triply lethal" in an interview (due to the fact that she was based his own three sisters he grew up with) and said that D.W.'s act of dressing up like Arthur and copying his actions in the episode "D.W. the Copycat" shouldn't be imitated by children.

The varying levels of the sympathetic-ness of her character throughout the show combined with the aforementioned Word of God statements make it extremely hard for me to tell if D.W. is actually meant to be a full-blown Hate Sink or not.