I've watched a lot of his TV shows and on the few where that particular type of collar is used, he's demonstrated it by placing it on the owner's arm. It doesn't deliver a shock, it's more like a mobile phone set to vibrate. When he's demonstrated it on the dog, the dog's response isn't pain or shock it's more a puzzled "WTF?" response.
A lot of the problems he deals with seem to stem from owners not having much clue about how to care for a dog. I would have thought it was obvious that dogs need exercise, and they also need boundaries, but a lot of his TV programmes seem to involve owners who haven't thought things through and ended up with problems they don't know how to solve.
Dogs don't appear to be afraid of him, and when he asserts his authority many of the dogs seem to be perfectly happy with that. Some of his cases have involved anxious or frightened dogs and he's resolved those and shown the owners the techniques for dealing effectively with that.
I know that many people don't ascribe to the "pack leader" concept, but if a dog is confused or unhappy as to how they fit in, as many of his cases appear to be, then I can understand how a dog can respond positively to someone who does give clear signals about what is acceptable behaviour and what isn't. Dogs are naturally gregarious animals, but they can't fit in to either a "pack" or a family if they're not given clear and consistent signals.
Watching the Dog Whisperer is like watching Supernanny. And a lot of the solutions seem to be the same ? understand what your dog/children need both physically and emotionally, clear and consistent boundaries about behaviour (including owners and parents), make time for talking with children/walking with the dog, watch their diet, etc.
As for a question ? I'd ask what his advice is for people being confronted with an off-leash dog and how to interpret that dog's behaviour.