Don't blame whomever... All kinds of stuff can end up in your cache that you didn't intend. Popups that you didn't ask for will leave urls in your cache. Images of porn can end up there from ads on pages that you have no control over. And most computers have viruses and trojans that seek out this stuff. Some email clients also interact with the browser for html email, so spam can leave bad traces in your cache. I'd be surprised if you can get around on the web these days without some of that stuff ending up in your cache. Instead of spying on whomever and looking around in the cache, try an open discussion. If if is a kid, you are never going to be able to shelter them from pornography on the web. It is too ubiquitous. It is everywhere. You can't block it with cybernannies etc... Kids are smart. So, instill your values in your kids, and hope they will make the right decisions. If it is your spouse, lighten up. There is a lot worse a person can be doing other than pursuing curiosity about sex. You might broach the subject with the person by saying something subtle like: "what can donkey$#%&ers.com offer you that I can't?" and watch their jaw hit the floor.