Someone I know hired an experienced programmer from Indian who interviewed well. When his first day started, he seemed extremely junior - needed basic things explained to him like command line usage. One of the people who interviewed him saw him on camera and told the EM he was pretty sure it was a different guy. The EM confronted him and he admitted it, so they let him go.

Makes me wonder what % of the time this actually works and no one is willing to fire them, or if it's just worth the salary of collecting a month of pay before you're found out.