Golly, what is a cleaning? Surely it won't be horrifying or otherwise discomforting ^_^ (<- clueless)
The Coordinator: When mortals are being too troublesome we have a procedure we begin. We leave the planet to focus on information cataloguing, and when is is completed we send out large, star-shaped constructs to sweep the planet and collect as many of the mortals as possible.
The Cartographer: I hate Cleanings, and I always object, but my vote isn't counted because I almost never participate in Collection missions. The Curator hates Cleaning as well, partially because the massive influx requires her to quickly design and construct huge wings of the Archive to store them, and then she has to start organizing them continuously, with no break, until the sweep is concluded.
The Coordinator: Yes, and once the sweep has finished we determine if we have Collected sufficiently from every species. If additional sweeps are deemed necessary we initiate them. If we have Collected sufficiently we commence the final step where we use our magic to begin to heat up the planet until it can no longer support life. This ensures that life will not re-evolve on that planet. We could move the whole planet out of the habitable zone to achieve a similar effect, but that's not allowed because it would unnecessarily disrupt the rest of the solar system. And cooling it is a bandaid at best, since it will re-warm in a few hundred, maybe a thousand years.
The Charmer: Wow, what a detailed description that I don't think you should have said, Coordinator.