I realize that this is a fairly small concern, but I wonder whether providers would generally prefer to receive their fees in C-notes or in twenties.  C-notes have the advantage that the money can be counted almost at a glance, which perhaps saves awkwardness during the session (even if the client leaves the envelope to be inspected while he showers).  But for day-to-day spending they can sometimes be cumbersome and conspicuous; while for a sexy woman to deposit quantities of them regularly in her bank might conceivably give rise to all-too-on-target speculation among the tellers.