Assuming that you are engaged in conversation/argument/debate with a specific target, perhaps the best way to edit out spurious strawmen is to mentally append "except in this case...." to any objection.

Thus:

Them: "It's important to be yourself."

You: "Except in this case, because John is a psychopath."

(Or, You: "Except in this case, because John is a fine, upstanding young guy... oh... nevermind.")

Not only should this eliminate most straw men, it should help keep the discussion on track.