Cleanliness is an essential part of the procedure, not only is there risk of superficial infection, but since there will be an incision (cut), infection could spread internally.
Of course, it's not often that you let a big bloke with a wet-wipe at your wedding tackle, but thoughts of septicaemia (blood poisoning) outweigh the disadvantages.
If you enlarge the picture, you'll notice that the opening to the surgeon's glove is bubbling. Either it's detergent from washing his hands thoroughly, or it's the start of a good caption competition.
