Sowa, your trainer is AWESOME!!! That is exactly how I feel.

To assault a dog's nose and eyes is to take away survival tools. It is shocking and scary to them, not exactly in the painful way that shock collars are, but it's still a harsh aversive. I agree that I would use a citronella collar as a last resort (NEVER a shock collar... it's never worth risking your dog's safety, and possibly making them very aggressive), but it's much better to actually WORK with your dog! I'd honestly rather get my dog de-barked, if it came to that, than hurt and confuse them with correction collars. What people don't get is that dogs are adapted for survival and for quick assocations - you can't plainly tell them in English, "look, buddy, if you bark I'm going to shock/citronella you". To them, they're thinking "ok, so when I see another dog/person walking by and I get scared, I experience pain and discomfort. those dogs/people are even scarier than I thought!"

Dogs don't bark incessantly just because. The majority of the time, dogs who bark have fear/aggression issues as well. They bark because they're scared. By not addressing the issue and working only to extinguish the symptom, you're getting nowhere but at best you'll get a really shut down unhappy dog. Shock and citronella collars only exacerbate the fear. Most obsessive barkers are also very underexercised and unsocialized - a tired dog will be cuddling with you, chewing on a bone, or napping - not spazzing out barking. Get out and socialize your dog, make his experiences with other dogs and people rewarding and positive, and tire them out so they aren't letting out their pent up energy with guarding behaviors.

Fozzie, being a Corgi x Husky, was naturally a barker when I got him. I don't tolerate unnecessary barking, so I addressed it immediately. My trainer told me to restrict his access to the front windows of the house, but that's unrealistic and just avoiding the issue imo. I kept a squirt bottle, clicker and treats in the living room/kitchen for a few weeks. When he started barking, I would "shhh" and squirt him to interrupt, he'd be called over and lots of click/treats then walked to the front window to LOOK AT the dogs and people walking by, and lots of click/treats to associate that stimulus with good things. On walks and hanging out in the front yard, I'd tell him to look at passing dogs and people, then click/treat repeatedly. This conditioning process made him see other dogs and people passing by the house as a wonderful thing that brought happiness instead of stress and overexcitement. Yelling at a dog only increases stress, and it's basically you joining your dog in the bark-fest.