On Fluther, I would, and have, absolutely done it, because this is a forum for getting answers, not for furthering people’s lies and foolishness. Also, when people on Fluther start accusing someone of being mean for pointing out the truth, they need to be reprimanded, publicly and privately.
At work, I’ve had to go to bosses when someone was doing something dangerous that could actually kill someone. Think power tools and machines.
On Facebook, I’ve had to do that when one woman didn’t believe there was such thing as a peanut allergy. My friend has had a severe peanut allergy her entire life and has been hospitalized multiple times for anaphylactic shock. Her relative doesn’t believe that peanuts are harmful to anyone and this woman made some foolish remarks in front of everyone at a restaurant when my friend asked (as she always has to) whether or not the dish contained peanuts. So the woman, who I have never met (so cannot admonish privately) made a bunch of false and dangerous statements regarding peanuts allergies (or the lack of them, in her opinion) on Facebook, so I called her out on it.
I don’t really care whether or not people call me mean, or a bully, because that simply isn’t the case. I know some of you, here on Fluther, would rather coddle the crazies, but I won’t do that. Also, I don’t just call them out publicly, which is what they need, lest other Jellies have not already figured out the deceit because they don’t always read all of the pertinent information, I also let the mods know. There’s no point in talking to these people privately, because then everything turns into a he said, she said. It’s best to let the mods work it out with the person, but it’s important to let them know, because they can’t be everywhere at all times. If they think I’m doing something wrong, they’ll let me know.