Siren Song - S5-E4
Character mistake: When discussing how best to help Melissa, Piper tells Paige that her birth father was half whitelighter, when he was fully a whitelighter. (00:25:15)
Character mistake: When Miles is shot, the cops apparently don't think it's necessary to tend to him to see if he's okay.
Character mistake: Paige goes undercover into the demonic market wearing a bright blue dress and blond wig, and none of the demons seem to notice she sticks out like a sore thumb.
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.