It's been shown that telling someone you're giving them a placebo can still bring benefit, in which case I'm okay with it. But giving someone a placebo or homeopathy pill (same thing) and failing to disclose it contains no active ingredient is pure deception, unless the patient has given consent that they may receive a placebo, like if they're in an experimental trial. Even if someone does show improvement after receiving the placebo, it's never justifiable to outright lie to them.