Money does not smell (lat.Pecunia non olet) - this is a catch phrase that came to us from ancient Rome. This phraseological unit means that sometimes it does not matter in what way the money is received, even if not in a completely honest way. Such a phrase could well have sounded from the lips of a bandit or a cunning businessman, but in fact it was uttered by one Roman emperor during a quarrel with his son.
Emperor Vespasian, in search of additional sources of replenishment of the treasury, introduced a tax on public toilets. Or rather, he made them paid, citing the fact that the treasury spends money on cleaning latrines. When his son Titus expressed his displeasure at the fact that Vespasian introduced such an "indecent" tax, the emperor said the phrase: "Money does not smell".
This is how the story is described in the book of Guy Suetonius Tranquill "The Life of the Twelve Caesars"
Titus reproached his father for taxing the out-need; he took a coin from the first profit, brought it to his nose and asked if it stinks. "No, " Titus replied. “But this is money from the urine, ” - said Vespasian.
The emperor's calculation turned out to be correct - the treasury was replenished with new income, and the expression "money does not smell" eventually acquired a meaning, indicating a not entirely clean source of income.