Even being a Public Establishment, open for everybody, when the Ridotto was made legal in 1638, some rules were formulated which regulated who would be admitted to enter, and in was the Nobility only, in the end. Oh surprise ...
There was sort of a dressing code, that went as follows, for men:
It was a little less defined for women, as long as they were wearing a mask.
Hidden identity was really paramount in those times, and less affluent Venetians were thereby prohibited from making wagers at the casino's tables.
Only the “barnabotti”, the croupiers, would appear with bare faces. The name is coming from a a poor neighborhood in Venice (San Barnaba). Usually the barnabotti were impoverished nobles, with a special preference to those who had lost all their belongings at gambling.
You gamble ... you lose ... you serve the others gambling ... and the wheel is turning!