So I have a Corsair 4000D air flow, and the top of the case is like full of holes to allow airflow (with a dust filter on top of it).
Thing is, I put the case more or less below where my hand is touching the mouse, to the right of my feet.
And, well, I could wash my hands or otherwise have my hands be slightly wet at some point, so I am afraid, those holes would be easy for a drop or two of water to fall down on the PC components.
How often is kinda like it depends. But I mean, it can happen, my hands aren’t always perfectly dry, I might even forget to dry them properly. I try to be careful now, but it can happen.
So, like 10-20% of the case is not under, I can’t push it entirely back, but I could push it back some more (and even then, drops of water don’t always fall perfectly vertically, so movement of hand can throw them under the desk anyway).
No cloth mousepad, I don’t even use a mousepad.