They start an argument hoping the other person will respond, and then they taunt back, often using a closing statement asserting some kind of weakness or fault in the OP. This is intended to get that person to emotionally respond again.
After several rounds of this clogging up a thread, other readers will drop out because the thread is hard to read with true content buried in the back-and-forth attacks.
Don't fall for it. Just let it go. If they persist, report abuse and move on.
-PJ
bttt