Personally I don't use Ad Blockers just due to the fact my own personal ethics feels I am stealing when I do use it. When I am teaching I have ad blocker installed because I don't want to get in trouble for what advertisement will be shown, especially YouTube. AdBlock Plus and their paid white list is the worst and I don't know why people use them.
I don't use AdBlock Plus but i do use AdBlock. I think its my decision to choose which ads i watch and which i don't. It's not stealing, Webmasters can detect if someone is using AdBlock or not.
In other words it's not stealing unless you get caught?
Edit: Relax people. Let's not get into another debate on copying vs. theft. I was merely pointing out that the parents analogy (which was the one that referenced stealing) was bad.