After I read this over again, I don't think I made it clear enough...sorry...
1)They yawn...so it would be a fairly quick opening and shutting again.This is nothing to be concerned about.
2)They open their mouths when angry/upset with someone or something. (Gapiing.) Although youi don't want this to happen all the time, its not a problem for it to happen sometimes.
3)They open their mouths when they are overheated to help themselves cool off. This is also not a problem if they only do it for a minute or two...but if they sit in the basking area with their mouths open for long, it likely means that you need to lower the temperature there.
4)They open their mouths and raise their head when they are swallowing water while being misted or under the dripper. This is normal as a rule.
5)They open their mouths and sit with their heads raised when they are dying...suffering from organ failure, etc. Well...I think its obvious that this is not good and the chameleon is sick.
6)They open it when they have a respiratory infection but then you will likely see a lot of extra saliva in its mouth and likely hear popping/wheezing noises when the mouth is open too...and it will keep it open for quite a while. If it has a respiratory infection you will need to take it to the vets to have it treated.
Sorry...I should have been more clear.
