Adultsites and proxyservers of big companies

[cow]

Within many big companies proxyservers prevent surfers to go to pornsites :-)
The companies I worked (I will not mention them here) though had pretty simple settings.
The proxy just looks at the domainname or a substring within this domainname like XXX, SEX, PORN or ADULT.
Sites like TheHun and BlinkingCOW pass by the proxy easily :-)
Sites like Worldsex and Adultfun gets blocked.

Does anyone have any experience with this ?
Experience in the sense of how many people are surfing adult sites during their daytime job ?

Now I know why TheHun is the biggest :-)

Moo