"I don't have a wardrobe, I have clothes," he said, mostly to be annoying. She was gone in the next minute, leaving him behind to find the Floo powder. It took long enough that he was on the verge of realizing exactly what he was doing -- fortunately, at that point, he found the jar and threw a pinch into the fireplace.
This whole deception took a few steps, which should've given him yet more time to think about the stupidity of what he was doing, but Michael didn't. He stepped out into the fireplace at One Shot, and then Apparated back near Lavender's apartment building. If he'd taken a proper look at himself, he would've realized that Padma was unlikely to be fooled: a blind person would hardly have been fooled. His clothes had been hastily put on, and his shirt was open at the collar, revealing a rather condemning splotch on the side of his neck; he had the generally-rumpled look of someone who had just gotten laid. Then again, given Michael's lifestyle, maybe it wouldn't be seen as anything out of the ordinary.
Michael made his way up to Lavender's flat (again), and knocked, whistling cheerfully under his breath.