Wanted to share my conversation with one of the mods. Would like to get others take on this opinion. Will give kudos to Flip and the mods for letting the conversation play out. See below for some Q&A about shot glass method. My concerns in Bold.
flip69 2 points an hour ago
"behavior modification" should not be done on chameleons... period.
Have you tried? I think you're underestimating them.
Also this isn't behavior modification.... it's understanding how they see and recognize water and learning.
They've got some interesting quirks.
I should note that I don't recommend a "shot glass" for a sub adult or older cham... only the younger ones. I've always recommended a drinking glass (stout and wide mouth) for them. It makes access easier.
I know that this has been passed around and "shotglass" has become the standard language for many... for the same reasons as "misting/high humidity" as it's needed for young animals and not older ones.
The other user in the thread even admitted their cham has pooped in shot glass a few times. If your concern is bacteria then your greatly increasing their chances of being exposed by using this method instead of misting its just common sense.
When the chams get fully hydrated, they do evacuate their bowels. conversely they hold onto their fecal's when dehydrated.
So it's a good sign.
Also, They're not stupid. and will not drink from a clouded water container. It lacks the sparkle that they need to understand that the water is "clean". Of course if the owner doesn't clean the glass for a week, it's going to be a problem. But thats not a failure of drinking glasses as much as basic husbandry and upkeep.
as for the bacteria, they get more than enough of that from the crickets that they pick off (that have been feeding on the droppings) and it seems that they're resistant to the fecal microflora far more than we are.
What does infect them and cause problem are a few very common household bacteria (yes I've had them identified with my vet) that are found in those with lung infections.
It's thought that these have adapted to live on the saliva that's deposited on surfaces from leaf licking. which can happen very quickly with different bacteria and fungi. (personal lab experience and food sources for culturing)
I have absolutely NO problem with this method being used IN CONJUNCTION with misting and dripping
Okay, that's fine and I do see that happening with people as well.
It's okay to be conservative with this and cover all the bases. I sure as hell did when I started switching over.
What I've had come back to me is that people are watching their chams go down and drink from the glass on their time schedule and not on the mister or when the dripper is filled.
It's very likely that they've been doing this anyway from those other systems without the owners noticing or sharing the observation.
I have.
but telling keepers it is the universal solution to hydration is 100% setting them up for long term health issues and organ failure.
For the common species it sure is. We've had a lot of people come through here with severely dehydrated animals that have followed the current dogma and did exactly what they were told by "the breeders" they got the animal from.
The strain on the kidneys are damaging, especially in combination with the daily supplementation that I still see people following as if it was a cure all for a healthy animal.
Part of the problem is that most of the time with kidney failure (over and incorrect supplementation with a phosphorus containing powder) is that renal failure results on a month(s) long wasting away that the owners don't recognize and the vets might not test for.
People's animals just get sick and die either from renal failure or a secondary issue.
A major cause of this is dehydration.... and I can tell you as a fact that having direct access to water does allow for 100% hydration. Far more than leaf licking.
- There's also this little quirk in their behaviors that make them very shy about drinking and this prevents them from performing the action unless very thirsty or completely (fully hydrated) while being watched.
Sounds like you've never heard of a drainage system or bioactivity either. 
