Which computer cleaner to install?

[Aravisian]

@Luca_Pavan

zabadabadoo said that it runs clean up commands behind the scenes, are you sure it doesn't delete stuff without my consent and knowledge?

I am 100% sure. I can say this with a Lot Of Confidence because I actually have reviewed the open source code for Bleachbit and even offered a small correction to it here:

[FIX] Bleachbit checkboxes covered by scrollbar

One of the things I have always noticed about Bleachbit is that it very annoyingly covers up the Checkboxes in the vertical gtk box on the left side. The scrollbar covers about 70% of the checkboxes (where you checkmark or uncheckmark the options you want to be cleaned.) It makes it very hard to check the boxes on or off. I haven't used Bleachbit due to this annoyance... But as FrenchPress has praised it, I figured I would give it another chance. And there was that annoyance, again. So I navi…

What @zabadabadoo was referring to was that it runs the same commands that you would run in terminal behind that GUI screen. Not that it runs commands "behind your back" when you are not actively using the application.
BleachBit is not automated and it will not run at all unless you launch it and operate it.
It does not run in the background. When you close it - it fully closes and kills the process. So if you launch it again after closing it, it must fully initialize.