As a countermeasure to this, you can 'pepper' your passes or secrets with reserved letters / symbols that only you know about. For example if a pass is

    _SOSECRETOMG!_

You simply omit the exclamation symbol, and reveal the real pass which is:

    _SOSECRETOMG_

That's a very basic example, and can be made as complicated as your brain will allow. The older you are, the harder this gets to do small byte flips like this.