I love the clicker - it's an important tool in my toolbox and my dogs LOVE it when I use it.  It's a very clean and efficient way to let a dog know he is right.  I can click alot faster than I can say "excellent" (which is my special verbal marker).

What I don't like about clickers is the way they can be mis-used and create confusion and frustration on the part of the dog. Once a dog has learned how to learn and has a repertoire of behaviors, you need to balance the "yes you're right" marker with a marker that lets the dog know he is incorrect instead of letting the dog try to figure it out.  The "this is not correct' marker can and should be nothing more than a soft, quiet, simple 'no'.

I watched as someone worked on teaching her dog to take the dumbbell.  She clicked and rewarded each time the dog put his nose to the dumbbell - that was good.   Then it was time for a little more; teeth on the dumbbell or maybe a slight open mouth to the dumbbell. When that didn't happen and the nose to the dumbbell didn't result in a click, the dog offered a down.  Instead of letting the dog know the down was incorrect she got the dog up and tried again; with the same result. And on it went.  A better approach would have been to simply and quietly say 'no' the first time the dog offered the down, gotten the dog up and gently pressed the dumbbell against the dog's teeth and click that approximation.  And from there, move on to the next step AND be ready to identify both the correct and incorrect responses.

Free-shaping with a clicker is great for puppies.  I did this with Rudy when he was a pup to teach him that 'down' was not the end of the world.  Once a dog has learned how to learn and has a repertoire of behaviors, trying to free-shape a specific behavior results in confusion and frustration.

Using a clicker to teach a behavior is fun and can make the process go very quickly.  To be fair to the dog, the 'yes you're right' marker must be balanced with a 'no, that was wrong' marker.  Your dog will appreciate the clarity!