Everything Justin said is really right on. Most are just mean.
But I have tried to find a way to fix Chams with "People-phobia". I cup feed my chameleons... And whenever possible I hold the cup in my hand.. reach in and present the food that way. I found that if you continuously feed the cham this way... They begin to learn that when you are around that normally means food. After a time...It will get to where when you come around it will almost seem like they are staring you down asking for food. I found that even the chams who like to retreat to hide when the cage opens, over time, with cup feeding by hand, they will start to instead approach you for food when the cage opens. I imagine this may be hard to do with a cham that is a little more mature, and not used to feeding this way.
With my 5 month old veiled Lombardi, who started getting his "tough guy" Veiled attitude as well, I have offered him food like this since I got him at 2.5 months. Now I am at the point where every now and then I offer the cup of food by extending my arm up into the cage... and holding the cup next to my arm around the elbow, so that he can look into the cup and see the prey. He comes out of the cage, and about half way down my arm to nab the prey, and I sit very still and let him sit and enjoy it on my arm. I then allow him to crawl back into the cage to go bask. This is getting the cham used to my interaction... on his own terms, and I have found has boosted my Chams comfort level around me. I do not do this so that I can "play" with my cham... or have fun cuddling him. I have just found that with some display animals...If they are affraid of you...or uncomfortable around you... They end up pretty poor display animals, when they hide everytime you come in the room. Just a little tip I use that may work with some... and may not work for others, every cham is different.
~Joe