Short answer: Not very, at least not with the Flame/Toxic Orbs.
Long answer: It occasionally sees use, but it's not very good. Rotom-Heat very rarely uses a Flame Orb and Trick for guaranteed burns, as opposed to Will-O-Wisp's 85% accuracy. This is extremely uncommon, and I haven't seen it in a very long while. Lopunny sometimes holds a Toxic Orb, which it can't be affected by due to Klutz. It then passes it off to an opponent to wear it down. Clefable, as it has Magic Guard, can do essentially the exact same thing as Lopunny.
There's just too many things that can go wrong. A faster Pokemon can Knock Off or use Corrosive Gas (but who uses that) to render your whole strategy useless. Alternatively, your Pokemon can pick up an item that cripples it. For instance, Lopunny getting passed Choice Specs, or Rotom-Heat an Assault Vest. It can be useable, but it's usually unviable. If you must use the Trick strategy, pass off something that can be more debilitating, like a choice item.
Hope I helped!