When you moor a boat, you attach a boat somewhere. Venice is a city in Italy with a lot of water channels that boats can travel on. "Moor" sounds like the word "more". The people in this joke did not want to see any "more of Venice". This joke is playing on the word "moor" because it relates to attaching your boat somewhere, and it's a homophone of more.
The tired playgoers decided to bypass the new production of ' ' Othello ' ' despite the good reviews ; having just returned from a long trip , they didn ' t feel like seeing any moor of Venice .