There's no rhyme or reason to the t-bagging I see. Any and all classes. Whether they killed you or not. Another player during a strike before they revive you. A member of an opposing team, t-bagging the wrong body (he was bagging his team mate).
I only t-bag after killing someone while they have super or holding a sword.
Today i got matched with two 228 in vanguard heroic. Everytime they died i t-bagged them untill they rage-quitted. Come on guys, recommended light is 265.
Tea bagging unleashing the inner demon inside the person making them see red its basically a taunt which can turn you into a vengeance seeking killer ooooor you can ignore it.