Comment by card_zero

Shades of Cyrano de Bergerac and pig-butchering scams. Which lead me to read about Milgram's "cyranoids": https://en.wikipedia.org/wiki/Cyranoid

And then "echoborgs": https://en.wikipedia.org/wiki/Echoborg

On the whole it's considered bad to mislead people. If my love letter to you is in fact a pre-written form, "my darling [insert name here]", and you suspect, but your suspicion is just baseless paranoia and a lucky guess, I suppose you're being delusional and I'm not being rude. But I'm still doing something wrong. Even if you don't suspect, and I call off the scam, I was still messing with you.

But the definition of being "misleading" is tricky, because we have personas and need them in order to communicate, which in any context at all is a kind of honest, sincere play-acting.