Of coarse!! Hehe. Most of the time when they fire up, and gape mouth open at you, they're just doing it to show you how big and bad they are. Most of the time they have no desire to bite you even when they're doing this. However, sometimes if they're is a bad enough mood, theyll bite you no questions asked. Even when they do though it really doesn't hurt to bad. Usually its just a bit of preassure and thats it. I've only had a cham break skin twice on me. And it was the same Veiled both times.
Even when they're mouths are open, most of the time you can even put your finger in their mouth and they still wont bite down. When they do its just a warning bite. They put a little preassure on you, let go right away, then try to escape.
P.S. Just for the record, I dont recommend getting your cham pissed off just to see if it will bite you. I may have done it a couple times while I was learning their personalities, but that doesn't mean I condone it. Chams like to be left alone, and getting them all riled up just stresses them out and should be avoided.