Out of curiousity, what sort of social reprobation do you think is acceptable? What is the line?
This is a difficult question, because I don't think that "the line" is static; there are factors involved depending on your relationship to the person in question, the nature of the reprobation you're expressing, etc.
I can tell you that personally, I don't like the idea of sharing personal condemnation of others in a public forum. Even leaving aside the self-aggrandizing nature of this (e.g. "I'm upset, and when you hear about this, you'll agree with me and be upset too!"), I find that attempting to shame someone in public tends to either 1) magnify their misery if they already feel bad, usually to the point of making them feel defensive (which tends undercut any process of self-examination they might otherwise be undergoing), or 2) be an instance of someone trying to promulgate their particular viewpoint by using demagoguery to scapegoat someone else.
I should mention that in this case, "public reprobation" is understood to include explicitly identifying someone else in the public sphere. It's one thing for me to say I hate some of the people I work with - you don't know where I work, or whom among them I hate. It's quite another thing to say that I overheard these two guys making a joke I found offensive, include their names and pictures of their faces, and support a petition to have them be fired from their jobs.
Personally, my two lines are: (1) I shouldn't lie about someone, although I can express a judgmental opinion, and (2) I shouldn't drag in people's personal lives or in general make it into a personal issue. This is not an absolute, but in general I prefer to talk about what someone writes/creates, not about who they are as people. However, if by telling the truth and expressing my honest opinion, I hurt someone's livelihood, that's not my problem. Yes, stuff like bad reviews and bad word-of-mouth hurt writers, but that shouldn't stifle how we speak (in my opinion).
I feel that you're talking about two different things, here. It's one thing to express your opinion about something, or even someone, that you don't like. It's another thing to use the public sphere as a weapon to attack their ability to operate within said public sphere (usually economically). Saying that you don't like person X's work is one thing, but starting a petition calling on company Y to fire person X is something else again.
I'll admit that these can be something of a continuum, as there can be very little difference between, say, practicing a personal boycott and starting an organized boycott - the former is your personal choice, whereas the latter is attempting to put a barrier between the person and those who'd want to patronize them.
Just to be clear: This is the Internet. People of all ideological stripes will act like assholes. Some of them will guaranteed lie, troll, and engage in other bad behavior - up to harassing, libeling, and/or threatening. I'd like standards of behavior to improve, but that can't be done by attacking one ideological side or the other.
I don't disagree; it's the nature of the tactics that I'd like to see change for the better. That said, people tend to go for what's most effective in removing the things they don't like, in my experience. When it's something they condemn, a lot of people are happy to adopt a mindset of "the ends (getting rid of this thing) justifies the means."