Why say "money does not smell"?

Why say

appears, so often used the phrase "money does not smell" comes from ancient Rome. As it turned out, these words left the Emperor Vespasian language, at a time when native son shamed head of the family for a tax to use the toilet in public places to enrich their coffers.

In response to this, the emperor's son offered to smell the money collected from paid toilets, and answer whether they smell. To which the answer was "no, do not smell." Since then, the phrase "money does not smell," began to be used frequently, but pay toilets steel and feature of our times, as well adding to the pocket of their respective owners.