Let's start a discussion by me asking this, where do you all draw a line for a story when it starts bashing a character? What are your limits on mistreatment to a character or group of characters before deciding that the author or group is not worth your time?

For me, it is when a mean-at-worst-but-still-not-a-complete-devil character (such as Blueblood) or a passer-by but supportive character (such as Flash Sentry) are gleefully getting completely ripped apart for the fact that they either exist or rejected one of the mane six.

What about yours?

I don't like when characters are being jerks because the writers wants them to be jerks, as to make a point that some other character is right. Or when they are being incompetent for the sake of the plot (Celestia, is going to develop PTSD over getting hit with the idiot stick so hard and so often).

I think that the problem is what the author intends with his story. There could be a genuinely good story about how Blueblood is psychopath using his station to do heinous acts, while maintaining an appearance of being noblepony with too high a opinion of himself. I probably wouldn't enjoy this story, but I know some people would like it. I think it would be difficult to write properly, but it's doable. Think Red Eye in FO:E. This is different from a story that has a clear goal in mind but keeps turning other characters into monsters just to hurt some other character. I'm thinking about Shining Armor and Luna in "Bringing Up Blueblood", used with the intention of creating difficulties for Blueblood; and (people are going to hate me for this) Eternal. I haven't read Eternal, but this seems to be going on in the story as I saw by comments and by the TvTropes pages. Honestly, it turned me away from the story.

I don't know. It's kind of a gray area to me when the author creates a situation to justify character bashing and it usually makes me wonder if I should be wasting my time reading this story. I think that your example of Flash Sentry is a good one. People just love to hate him, and writers keep perpetuating the producers' mistake, in the cartoon, of using him as a cardboard character to fit in a hole, instead of giving him a personality and a reason to exist.