It's not pretty but at least you don't lose your item. Only those with Mega evolution can take the risk of switching into a knock off while avoiding losing their item, and out of all mega's I'm aware off, only T-tar, Mawile and Houndoom resist dark attacks.252+ Atk Life Orb Bisharp Knock Off vs. 4 HP / 0 Def Mega Houndoom: 81-95 (27.7 - 32.5%) -- guaranteed 4HKO
Losing a third of your health and a weakness to sr isn't pretty, especially if you no form of recovery.
Knock off is really an ugly move to face, especially if your team depends on knock-able items like I do.