I think it is Tacitus who relates the story of Vespasian's efforts to stir up more revenue for the imperial coffers, and how he decided to start charging a tax on every person who used Rome's public lavatories. While out walking with his son Titus soon afterward, Titus raised the question of whether it was a good idea to tax the people's access to places wherein they took care of necessary (if frequently distasteful) body functions.

Vespasian's reply was characteristically blunt. Waving a gold aureus under his son's nose, he said, "Breathe deeply. Money has no smell."

(this is written from memory, and therefore the details might be bit off the mark, but the spirit of the anecdote is spot-on.)

All the Best,

Quint.