Personally, I have no problem with being attacked on intellect, anyone is welcome to call me stupid etc. I am mightly tired of of the personal comments about sex, gender, race, sexual preference, looks, weight, etc. Those insults, to me, are unnecessary and show a decided lack of character in the person who says it.
To be clear, in my opinion, anyone who uses any of the above is a moron who is not worthy of entering into any discussion whatsoever. Those people, and you know who you are, are moronic fools.
For the record, I did it once.... I am not proud of it, but as soon as I realized that I had actually hurt that person's feelings, I apologized. That's because I am actually a grown up.