I've a couple of bad experiences with being hassled and arrested by cops that i've written about here a while back. I got attacked by some idiot once and that story is here: http://www.hookahpro.com/forum/showthread.php?t=373
. My guess is that people think that what he do is illegal partly because up until about 10 years ago almost everyone that smoked a narghile in the Western world was doing something illegal. It doesn't help that a huge range of stores and websites peddle shisha related products alongside gear that clearly intended for use with illegal substances. Other then that I think we are just dealing with stupidity.