This is a basic reality of all MMO's. PUGS = griefers, leechers, leavers ... nothing will change that. If you want to be free of griefing, join a fleet. If you need to farm STFs in PUGS, accept the fact that a percentage of runs will fail due to the aforementioned player types.

PUGS are like a box of chocolates, you never know what your going to get.