I had a guy in one of my Oryx runs last week that was stoned out of his gourd. He was a self-res warlock, and it was a good thing too. The guy died every two minutes and caused a handful of wipes when he didn't have his super up. He even died during the Sisters fight somehow, and all he had to do was stand on a plate for 20 seconds and shoot a sniper. Sniper got him. He could not for the life of him kill his knight during Oryx and every time we asked him if his knight was down he stuttered and acted like he had no idea he had a knight to kill. At one point he even said "I can't even keep my eyes open bro". He left on his own just before the Fireteam lead was about to kick him. The occasional high guy can be entertaining as long as he's not dragging down the group. And I've probably raided with tons of people who are high but keep it quiet, don't announce to the world how cool they think they are, and have the self control to not become totally useless.