Ethical – that’s questionable. There isn’t one single answer, because it’s based on the morality of the preying. Legal, absolutely. Politicians have gained huge power that way. Just look a Trump. And corporations have profited for a 150 years on the gullibility of the masses. And let’s not even start on religion, whose entire power structure and raison d’etre is based on selling people lies and hoodwinking them. Which raises a different question: can religion, which is supposed to give guidance for ethical conduct, do unethical things?