Mac cleaning app?

What experiences did you guys make with Onyx? I read several times that those cleaning apps mostly make the Mac worse than before. I used some of those cleaning apps when I was still on Windows and it always helped a little, but sometimes nothing would work after deleting "unwanted" or corrupt files / registry entries.
 
See, OS X isn't as bad as windows when it comes to the "unwanted" files, registry errors and that kind of thing, so the "cleaning" apps don't have nearly as much work to do.
OS X runs its own daily, weekly and monthly maintenance scripts anyway (which can be run manually from Onyx too) and the file-system is self-defragging, so that's another major problem out of the way. the only regular maintenance a Mac needs is to Repair Permissions every few weeks.

The only other thing I use Onyx for is to change the Dock to 2D mode to get rid of that dumb reflective look.
 
Manually cleaning out certain folders and caches every so often will create a lot more space and boast your performance. I have all my apps slimmed down to take up less space aswell as certain binary ?codes/architecture? deleted. Apps like Monolingual will delete language resources so your just left with English. Its amazing how many GBs language packs take up. Also only installing AU if your just using Logic will save on space, theirs no need to install RTAS and VST aswell. All these little things ad up and will speed up your Mac but you have to know what your doing or you can really eff things up.
 
Been using Onyx for a good year now. For me at least it greatly improves the overall performance. If I forget to do it every once in a while I can def notice a difference with the system bogging down a little bit.