Continuity mistake: Paige looks in the Book of Shadows and suggests that the demon they are looking for could be Belthazor, not knowing that Belthazor is Cole's demonic form. But we saw Phoebe making extensive changes to Belthazor's entry in the Book of Shadows in a previous episode, and the changes are not in evidence here. (00:01:40)
Continuity mistake: After Phoebe finds the Scavenger Demon page in the Book of Shadows the camera dollies out, and when Piper asks what happened with Cole, the crew's taped black mat is visible on the bare floor with no fringed area rug, then when Cole shimmers into the attic, in the next shot of Piper and Phoebe we see the fringed area rug at the bottom of the screen. (00:06:35)
Continuity mistake: When Phoebe tries talking to Emma about Belthazor, Emma's hands are folded in front of her, holding her sweater closed. In the following shot when Emma turns around, her arms are now down by her sides, with her sweater open. (00:31:10)
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.