As far as mistaking a man for Jesus, I can only think of Monty Python.

If we use the older word Messiah, or Moshiach, then there have been many, primarily in Judaism, and dating from before Christ to the 20th century. https://en.wikipedia.org/wiki/List_of_Jewish_messiah_claimants

What I said though was that I was concerned about an anti-messiah who leads, rather than to salvation through faith in God, to destruction through faith in falsity and idols, and Revelation states that there will be one who will be able to deceive even the elect. How many times this has or will happen, we don’t know, but there is at least one. An antimessiah need not claim deity, but only to be the deliverer. One could quite fairly consider, for example, Karl Marx to be an example of an antimoshiach, or Woodrow Wilson, or Jim Jones. These people brought destruction on their followers for listening to them, rather than merely failing, or enacting evil.

The ultimate antimessiah would certainly be quite deceitful indeed, so it’s good, as with Gideon, to always have our heads up.

As much as that, we should have some idea of how to accomplish the question, “if the Son of God, or an anointed of God were right in front of you, would you recognize him, and how?”