1 The most virulent trolls are always anonymous, too cowardly to identify themselves.
2 The most stupid comments come from those with the silliest phoney Twitter names.
3 The abusers usually have few followers but Tweet incessantly.
4 The less the troll knows, the greater the certainty with which he (and it is usually a "he") claims to know it.
5 And women on social media receive the worst abuse.