It would be faster to reformat and reinstall.
"Porn residue" could include viruses.
Yes I know that, but time I'm not so sure about, it takes hrs to format HD, but days, or even weeks to re-install everything. I was hoping for a program to run in the back ground and find stuff, then when it is done, I can remove what I want.
I would never ever put in use a used computer without doing a complete factory reset.
You have no knowledge what kind of malware, spyware or other software is installed that may leak your personal information.
Of course you know that it isn't quite that simple, there isn't a magic "reset button" as with cell phones.
If the previous owner took the time to perform a backup, who knows what was already on the system prior to running the backup.
OEM PCs do not ship with disks or partitions installed anymore, but it may be possible to go to the manufacturers site and download a copy of the OEM OS install disk.
System restore works for OS issues, but it doesn't delete files.
I don't really see a big issue with using an "in service" OS on a used PC, for the novice it's much easier to clean out the unwanted files, folders, and apps than to format C:\