What are these bugs and are they a bad thing?

[Guinnik]

I have noticed tiny brown crawlies around the air vent and inside the vent itself.
They are very small and brown, at first I thought it was spilt coffee grounds.
Does anyone know what they might be?
I've poured a little boiling water on them and am keeping a daily check at present.

[Penguin]

I have these too around the edge and hinges of the Hotbin lid. Hopefully someone can tell us what they are.