Dog clickers are good if you know how to use them.
It is used as praise for good behaviour.
It is a case of praising the good and ignoring the bad behaviour.
when starting to use it the clicker is used for instance, if you dog is told to sit and sits immediately, this is instantly followed by a click and a treat.
It works in some situations but not others.
If you are having problems with your dog that is getting out of hand you are best to go to a qualified, certified dog behaviourist for a dog assessment. From this you will be told the best action to take and will be guided properly.
I have used clickers on our pet dogs, but they are not totally out of control, and it has worked sucessfully and i have the dogs full attention when out walking.