LOL you must all be living a wild, secret life compared to me!
I clean things out normally...I obviously do checks for viruses and spyware and that sort of thing...and I make it a point to clean out cookies and history just for good ol' fashioned maintenance reasons. But as for hiding and burying and renaming files, I'm not doing anything illegal, so why bother going to TOO much trouble?
Besides, I figure the worst that will happen is someone will accidentally see something and say "Oh my! You've got some porn saved on your computer!" -- at which point I'll laugh and say, "Yeah, just like 99.999% of everyone else in the world!"
But these are good tips for many to know (or to at least consider), so it was a great thread to have started.