The other thing to keep in mind is that when you pay for the bandwidth, you are granted the right to impose whatever moral restrictions you wish to on how that bandwidth gets used. If someone doesn't like it, they are more than welcome to do their surfing on their own time.

Companies do indeed realize that not all of the internet use at work is for strictly job-related purposes, and that it's a bit of a "convenience" that is akin to providing magazines in the break room. But with that, there are going to be cases where a good employee gets fired for sending one dirty email or browsing one dirty website, while another slack-jawed stiff employee surfs the net 24/7 and keeps their job.