Ccleaner has had over 275 million downloads according to Wiki yet if you
search for "Ccleaner problems" in Google you find an absolute minimal number
of people reporting any and most of those appear to be related to something
else they'd installed and forgotten about. If it really didn't work there'd
be a damn sight more people complaining about it.
I've used it for over 2 years multiple times a day without a single issue as
have many people I know and it's one of the best little apps I've ever come
across. I wouldn't dream of trying to manage without it now. It lets you
customise every possible option but in any case the defaults are completely
safe. Anyone who pays for access to so called "Windows Secrets" which there
are thousands of free sites covering every topic imaginable must be nuts but
don't let that stop you from touting for more business.
To the OP, like any topic on Usenet you'll tend to find the good advice
drowned out by the scammers and the noise but no one can help you decide
which is good advice and which not. It's all worth at least exactly as much
as you're paying for it
When you spot someone with what appears to be a
vested interest you can generally safely ignore them though.