This is exactly what the OP was suggesting that you [i]not [/i]do. By skipping the "trash" mobs you are skipping potential drops. The mob level has nothing to do what what it drops. A buddy of mine was farming public events in the Cosmodrome with me and he killed a level[b] 2 [/b]Dreg. Dropped a Legendary Engram and got Gjallahorn from it. That's "trash". You need to reevaluate your logic.