Inane cliches/truisms you could go the rest of your life without hearing again

[Beet]

Voltaire? You mean it wasn't my high school history teacher? Damnnit.

[Okay, maybe Mike Johnson is a competent parliamentarian.]

'A republic, not a democracy'.

[The Mikado]

'A republic, not a democracy'.

Another for the "what the hell does this even mean" category.  In the modern definition, a republic is just a country without a monarchy.  North Korea, Syria, Russia, and the US are similarly republics, while Great Britain, the Netherlands, Saudi Arabia, and Brunei are similarly monarchies.  The word is utterly useless.

[pbrower2a]

That the Romans had orgies of wild sex.

Truth: the Romans were prudes, and when they had sex they were very secretive about it. They thought overt sexuality barbarous and depicted scandalous people in the sex act of some kind.

...Henryk Sienkiewicz (Quo Vadis) had his own agenda -- in his case depicting Nero as a mad emperor who persecuted innocent Christians and offended Christian morality at will. Change "early Christians" to contemporary Poles under "mad emperors" such as those of Germany, Russia, and Austria-Hungary) and you get the general idea. That is how things work with antiquity.