Some people - Crazy or Stupid!!!!!
Last night while levelling with my 5 man team (Prot Pala 70, 4x Elem sham 68) I was finishing up a few quests in Nagrand. Went to do 'The Ultimate Bloodsport' to kill Tusker when I notice a horde shaman 66 and druid 68, but think to myself there is 5 of me and only 2 of them I am higher level surely they will not be stupid enough to even try!!!! How wrong was I?! I drop my totem farm and get ready to pull Tusker when I notice the druid stealth, figure what the hell and pulled Tusker anyway. Yep you guessed it they attacked as soon as I had agroed Tusker.
I just switched targets for DPS and kept tanking macro going, they did get one of my shamans down (pressed wrong button and healed wrong shaman!!!! Stupid mistake). After about 15 seconds we have 2 dead horde, and quest complete.
Why did they even try???? Yes they got one guy down but that was luck. So I went on my way but the relised I had not picked up the quest item on one of my toons so went back and killed the shaman again.
Do you often come across people like that? It is the first time I have had any horde attack me unless they were lvl 80 who would just nuke my group in 2 sec.