You have rediscovered steganography (https://en.wikipedia.org/wiki/Steganography). Nothing new here on that end.

> How will we know in the future that what we are replying to is not some bot with alter motive?

How do you know today that you are not doing the same? How did you know last year you were not conversing with some bot? Absent some tell to indicate "likely a bot" you have no way to know with certainty.

"On the Internet, nobody knows you're a dog" (https://en.wikipedia.org/wiki/On_the_Internet,_nobody_knows_...)