How do you pretend you are surfing abroad?

Some years ago, you could set your browser to use a proxy server and surf the web as though you were in another country. This was a handy tool for us, as we often need to check that the ads being shown on our sites were suitable—you never know what ad networks might try to send through. We’ve even caught fake ad campaigns with nasties before things got out (we had a biggie in 2007 masquerading as a sits vac site), so it’s a useful thing for us to do for user security.
   Software, however, has got a lot better at geotargeting, and even our own in-house programs can see through proxy-surfing. Regardless of proxy server, our ad server knows where I am, at least as far as the nation (it can get the city wrong and even Lucire shows me a lot of ads for Les Mills in Britomart).
   Therefore, I’m curious: how can Joe Schmoes like me browse the web and pretend I am from somewhere else?
   VNC was mentioned as a solution, but it seems proxies won’t really do it any more.
   And no, I’m not interested in Hulu or any of those TV sites. I have my legally watchable Alarm für Cobra 11s from Germany, the odd doco on Swedish public TV, and Ecast TV, and I am quite happy on that front. Suggestions are welcome in the comments.