The "extra quality" descriptor often implies that the list has a high . While many public combolists contain 80–90% dead or fake data, "extra quality" lists can reach validity rates as high as 98% because they come from specialized infostealer campaigns. Risks and Impact Combolists and ULP Files on the Dark Web - Group-IB

You can neutralize the threat of combo lists by eliminating password reuse and securing your authentication methods.