Show Ghouls - S7-E15
Plot hole: When Leo tells Piper that he believes he found the demon Sargon in the Book of Shadows (which may be the demon Count Roget made a faustian deal with), Piper looks at it and says that they vanquished this demon five years ago. Which would've meant they vanquished the demon with Prue. When in fact the only demon that happened with was Zahn in season 6 episode 6, "Soul Survivor," and they did that with Paige.
Show Ghouls - S7-E15
Continuity mistake: When Phoebe is on the phone with Elise about the Cosmo interview, she jumps between shots from leaning over the kitchen table to sitting straight up. (00:05:45)
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.