If you detect a repressed smile on the salesperson's face, you paid too much for it. - Nassim Nicholas Taleb

The observation of the numerous misfortunes that attend all conditions forbids us to grow insolent upon our present enjoyments, or to admire a man's happiness that may yet, in course of time, suffer change. For the uncertain future has yet to come, with all variety of future; and to him only to whom the divinity has [guaranteed] continued happiness until the end we may call happy.

Complaints don't deliver complaints, they mostly reveal your weakness.

Another marker for charlatans: they don't voice opinions that can get them in trouble.