Yeah - we worked with a company that bought some traffic on a cost per impression basis relatively recently, and all of a sudden we had a significant burst in e

Yeah - we worked with a company that bought some traffic on a cost per impression basis relatively recently, and all of a sudden we had a significant burst in errors being reported. The user agent for the devices experiencing the errors were all an old version Firefox. Turns out that version of Firefox was the default for some version of Selenium, and all of that traffic was coming from bots running in data centers. Moral of the story, don't buy cost per impression from any company with anything but the best reputation, because that market is saturated with bots.