Why should the whole network suffer for the abuse of a few?
I don't think that we should focus on 'abusers'. From what I can see, even the heaviest bandwidth users (some of whom were awesome enough to post on this thread a while back), they have their reasons for using the bandwidth they do. I really believe that all of us have role to play in making an awesome network, from the lightest to heaviest users.
As I explained a few posts ago, the heavy users give us the ability to break through quotas and motivate for more capacity and better pricing, which benefits everybody. So we all need each other really.
Obviously anyone who is abusing the network through VPN/Sandboxes is not cool and they are in violation of our AUP. If we can can identify them (which is pretty difficult) then we do politely ask them to stop or leave