I believe in ultimate privacy and security over the internet and would like to be educated and hopefully educate others on important privacy matters. Basically the point of this post is to help me (and others) develop more knowledge over privacy and how CCleaner can support us in this aspect.
For example, as attached, I have the defaults selected and would like to learn more about what the other options do. Would it be safe to select all options they provide us? If not, what should and shouldn't be selected? And the ones I don't have selected, what do they mean? Can they damage your computer if you don't know much about the advanced/system area?
Most of your questions can probably be answered with the CCleaner Documentation or by searching the Forum. If you can't find an answer by either of those, searching Google can be helpful. Then if you still have questions, asking a specific question will probably get more replies.
Long story short, yes! Ordinary cleaners that search for file extensions to remove are very dangerous. Such as .TMP for Temp files, because you may have a program using a .TMP for a calendar template (different type of TMP file).
However, CCleaner does not do this & is 100% safe in the cleaning operations.
Instead of searching for files by extension, it has built in instructions on the exact folders to clean of junk.
This is what makes CCleaner one of the best.
Also, yes, it should theoretically be safe to checkmark everything, but why try to clean FTP accounts for example, if you don't even have those?
I believe this answers your question.
Don
Edit: The Registry cleaner part should never be used till you have to. It is the only part of CCleaner that is not 100% safe. It usually does good, but you do need to be very careful & really know what you are doing here, so that part is not recommended till you have experience under your belt.