One little trick I've tried a couple times is to run a proxy tester via a proxy. In other words, I test out a list from the forum with my own native IP. Save the successful. Then I retest the whole list with the proxy tester running through a proxy in another country.
Interesting idea...how many extra working proxies does this get for you on average?
Sage - out of curiousity - what app or language did you built your bot in? I've been thinking about similar things for proxy management in general.
I just started using an opensource tool called AutoIt. I know everyone here is using something like Ubot or WinAutomation, but I'm not going to pay the outrageous price for Ubot and I tried WinAutomation briefly and didn't love it.
With AutoIt, it's totally free and has a large community of people developing stuff to make it easier and extending it. You can pretty much do anything with it and it creates EXEs for you for distribution (sale).
This is my first bot, but I've made it so anyone can use it by just putting their own username/password for the proxy forum into the config file. It will log you in if you're not logged in already, go to the scrapebox section, grab the latest proxies, then it will get the proxies from the other sections as well (lvl1 anon, lvl2 anon, usa socks, and uncommon socks). It will write all of it to a data file and put the whole list into the clipboard for you. Then it will launch your SB if it's not already running, add the whole list to your proxy list, start the test cycle, and add the successful ones. All with one click.
It's not perfect as I've only done a little bit of exception handling in it, but it works for the most part. Of course, I've only tested it on my computer.
If proxygo is ok with me sharing this, I'd be happy to, but only with his blessing. Not sure how he would feel about lots of people using bots to get stuff from his site...of course, anyone who uses it will need to have their own username/password, but still...