Agree, trying to explain why people like Tor operators and/or volunteers on WGC are giving time, network/cpu computing, money... to preserve and help human rights, health... can be a good way. Trying to show them what the Tor network is, why, the goal... the easiest possible, because many of them are not geeks. Good luck...
Julien ROBIN :
In all those cases, my words are honest and true; as we shouldn't be ashamed of participating to projects aiming to a better word and more freedom, but shouldn't be happy of misuses, my personal preference is to be understanding and true. I also tell them that I'm participating, with my computers, to others scientific projects like World Community Grid (explaining it's about cancer research and a lot of others subjects) : It can be seen as "not related" but it is, as that's the way we are volunteers to the Tor Network !