I know lots of IT people that have worked for companies that pushed porn. If you look on their resume you'd see that they worked for "Lisbon Entertainment" or some other equeally unassuming company.
For the most part, no one knows what the company actually did unless they know someone else that worked there. But, unless you are modeling, your resume is going to mention things like the number of servers, server load, uptime rates and the tools you worked with.
I don't know anyone that's ever been hurt by working for one of the porn sites. The bigger embarrassment is when their friends/family ask them what they do for a living.