Might be a dumb question, but I was wondering if anybody has ever successfully requested an upgrade, paying in miles (on UA, I think it's 15,000 for a one-class upgrade on North America-Europe flights), who doesn't hold status of any kind. I know that it would take a perfect storm of low load factor, no status holders waiting for upgrades, traveling on a refundable ticket, and other alignments of the stars to do so. I've tried and failed multiple times and was just wondering if anybody else has successfully done this.

Thanks in advance for indulging my curiosity.