I was running a Walmart price monitoring pipeline for a client. 11 weeks in, someone noticed our competitor analysis was consistently off — the prices we were capturing were $5–$8 higher than what shoppers actually saw at checkout. The scraper wasn't failing. It was returning 200 OK on every request. It just wasn't returning real data. What's Actually Happening Walmart runs a bot detection layer that doesn't just block scrapers — it misdirects them. When your session is identified as non-human, the platform serves you a slightly inflated version of reality. Prices a few dollars off. Inventory counts that don't match. BuyBox sellers that aren't actually winning. It's called data poisoning, and it's designed to be undetectable if you're only checking whether your scraper returns a response. In testing across 5,000+ request sessions, I found that 34% of "successful" Walmart scrapes returned prices $4–$11 above the real checkout price . The session succeeded. The data was wrong.…