In the 'old days' Marrakech water sellers dressed in brightly coloured clothing and hats to advertise their services. Today they do sell water but they get most of their income from demanding money from tourists who want to take their photograph. If you have a good long lens find a concealed location and snap the picture. If they spot you then run.
Don't drink the water. If you are going to go to the Chez Ali Arabian themed dinner show they have staff dressed as authentic water sellers who will allow you to take as many photos as you like without asking for payment.
Beware the Jemaa-el-fna square henna artist as they may suddenly grab your arm as you pass. They will then thrust a catalogue of designs in your face and draw you towards other artists sitting on the floor. Even if you say you are not interested they may try to mark your hand with henna and demand money.
If you decide you do want a henna tattoo be aware that they can last up to a month. Make sure you confirm the cost before you have it done. Try to get them to write down the price as they have a habit of increasing the price after they have finished. Pretend you do not under stand how much it will cost.
Cobras and snake charmers
The area in front of the Bank in Jemaa-el-fna square is snake country. This is the area inhabited by the snake charmers and monkey men. If you hate the idea of touching a snake or having a snake put around your neck avoid this area at all costs. If a local motions you over to look at a tambourine on the ground. ignore him and walk away. They will try to beckon you closer and closer, and then they will suddenly turn it over revealing one or two hissing and spitting cobras that will suddenly jump up at you.
If you just want to watch the snake charming show just put a few dirham coins in the hat when it comes round. If you are lurking around the snake charmers looking at what is going on do not be surprised if they suddenly come up to you and put a snake around your neck without asking permission. If you want to have a photograph holding a snake or with one around your neck it will cost you. Haggle and get the price low as they will demand a very high price at first. Do this BEFORE the picture is taken
In the same area in front of the Bank in Jemaa-el-fna square you will find men with cute looking monkeys. Avoid them unless you want to pay a lot of money for a picture of a monkey on your shoulder. The locals with these cute animals are very friendly and pleasant until it comes to the fee. The same advice applies as with the snake charmers.
Haggle and get the price low as they will demand a very high price at first. Do this BEFORE the picture is taken. If business is slow they will search for a tourist standing still looking in the other direction. They will put a monkey on their shoulder and start demanding money to remove the monkey who is starting to pull at your hair. If you shudder at the thought of having a monkey or snake thrust upon you avoid the area in front of the Bank in Jemaa-el-fna square.