The problem is the concept of hijacking DNS in order to show ads or beg for money on a wireless network. It's like saying that you don't want hands because when you hit them with a hammer, they start bleeding all over the place. The solution is to not hit your hand with a hammer, not to not have hands. Because they're pretty useful except for the whole bleeding thing.

I was merely suggesting that changing DNS servers does not always work well in real life, most unfortunately.