I have recieved very few PM's but they have never been 'nasty' nor conniving. I would have immediately notified HQ and confronted the GN member in full sight if I had. I can see how some GN get close and I should imagine there is a nice aspect to sending and giving them.
I have noted some GN have mentioned they have however recieved nasty PMs.
I am now, having just read, 'Just want to say goodbye' on the ASK A GRAN thread, wondering if the fact HQ has declared they are aware someone has been on in more than one persona with the aim of causing trouble if this is a common problem? For all we know all the GN's who have recieved one have been sent them from just one person. Just a thought.