Does Costco flag you for returns?

I've been wondering, does Costco flag you for returns? I've heard some people say that if you return too many items, Costco will start to monitor your account or even ban you from making future purchases. Is this true? And if so, what exactly counts as "too many" returns? I'm curious to know if there's a specific policy in place or if it's more of a case-by-case basis. Can you shed some light on this for me?