Sleuthing With the Enemy - S3-E8
Revealing mistake: When Cole / Belthazar grabs Phoebe to use her as a hostage, you can see, very obviously, that he doesn't pull her. Phoebe actually steps in front of him willingly, despite the look of fear on her face.
Sleuthing With the Enemy - S3-E8
Revealing mistake: When Phoebe throws the potion at Cole's coat, the vial doesn't shatter, even though it sounds like it. Watch closely, and you'll see the purple, unbroken vial bounce off the coat and away out of shot without any of the potion touching the coat.
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.