You'd better remember to do "Erase Free Space" in Disk Utility every so often, or your "porn tracks" will stay on your comp until your HD fills up - 7331 hackers could expose your deleted files unless they're zeroed..... ..... of course I'm not paranoid! *clears all computer caches six times a day* What makes you think that?!
Or you could do Secure Empty Trash which zeroes them out. Correct me if I'm wrong, but my reasoning is that the files hang around, albeit unnamed, until they are overwritten after all the completely unused space on your HD is used up.