Glad I used the search feature. I was about to start my own thread about this same topic.
I have seen this quite a lot. And if you haven't, and look for it, you will too:
Person A receives a thumb down from Person B. "A" then follows "B" to their next post and gives them a down, just for retaliation. I have seen it follow to other threads. This is improper use of the feature just to throw a jab at someone. This is childish behavior.
As was pointed out to me, and I was well aware of it, the thumb down means "I disagree". Great, I disagree. I don't feel the need to trash their post though. I simply highlight the text, quote it, and state my opinion. Why can't that be enough?
The down does nothing to psk. It only trashes someone's post. And if it is being used correctly, then why does it seem so "focused" individually? Look closely and you will see two people saying the same things, but only one post gets trashed.
And "I disagree" is a very broad meaning. For what it's worth, I could left click all day. It is all about respect.
