What is pixel poisoning on Meta lead campaigns and how do I prevent it?

Pixel poisoning happens when low-quality or bot conversions are sent back to Meta as if they were real leads, so the algorithm learns to optimize toward more of the same junk traffic. The page recommends creating a verified-lead or qualified-lead event after the contact passes your checks, instead of firing a conversion on every raw form submit. BotRefund helps by flagging suspicious sessions before they contaminate the conversion signal Meta uses for optimization.