I believe if you use the collar in a negative way they can most definatly become collar wise. i.e. If a dog misbehaves in some way and you grab the collar and place it on him to punish then begin to stimulate for that specific behavior. Similiar to someone grabbing a newspaper and smacking the dog over the snout everytime a dog does an unwanted behavior. The dog will relate the newspaper, E-collar, or any positive punishment to correct that negative behavior. When you place the collar on the dog or grab the newspaper the dog will become nervous anticipating negative things coming their way.
The collar gives the advantage of not changing your body language or tone to apply the stim to communicate with the animal.The E-collar is just another way to communicate to the dog. You could use the collar the same way as a clicker and the dog would not no anything different.If you conditioned the dog that a treat was coming their way after a low level stim,the same as a clicker, you could use this tool as a "bridge" that could be used silently and at great distances.
If you believe the dog is collar wise then place it on the dog, without turning it on, and go about your business,walk,hike, or training. I am pretty confident if you take the dog around a high enough distractions over time you will find out the dog is not wise to the collar. If the dog was collar wise he would not test the limits anymore and never need another stim.
I do not believe the dog ever needs to be weened off of the collar. You never no when you might run into a new distraction that catches your dogs interest and he tries to blow you off. Training is never ending and will always require conditioning.It does not matter what tool you are using for training clicker,treats,toy drive,choke,prong,E-collar,leash or combination of any. Conditon the dog to a high level so that when the times the tool is not able to be used, such as certification of a sport, the dog will perform with a higher level of competence.
Think of the tool as a manager of any succesfull business or workplace. Now if that same manager was still around during work hours however stopped enforcing punishment for negative behavior from employees. If employees were able to now take off random days or drop production without being disciplined. After time the business would start to fall apart and production would decrease.