Some proxies were banned from Adsense or Google because they were listed on proxy.org

On many occasions, Google adsense account was banned because of traffic comming from proxy.org. The reason is click fraud on web proxies. It has also been noted that non-human traffic was coming from proxy.org by few peoples. I consider it would be safe to block that kind of traffic (though proxy.org can be a great source of proxy traffic ;) )

The code to block proxy.org:

RewriteEngine on
# Options +FollowSymlinks
RewriteCond %{HTTP_REFERER} proxy\.org [NC]
RewriteRule .* - [F]

You can change proxy\.org to any other url which you want to block - if the site traffic looks suspicious.