Its like putting a sticking plaster over a compound fracture!

Sadly there is next to no regulation in the dog training industry.
Anyone can call themselves a behaviourist or a 'dog psychologist'

There are some amazing ones out there who have spent years studying, researching and then gaining hands on experience, who also still continue to learn the most up to date methods.
In the UK these people can be found in organisations like the APBC's

Sadly there is another group of people who call themselves dog psychologists.

And they spout some stuff that can sound good - about treating your dog like a dog and things like that.
But
They actually know nothing about psychology - or just enough to be dangerous

Psychology is the scientific study of how the mind works and how that can effect behaviours.

Often a person will go to a 'behaviourist' with aggression issues - dogs barking/lunging or even fighting with other dogs.

An actual behaviourist is interested in finding out what is going on in the dogs mind and then changing the reason for the aggression which in turn makes the aggression go away

A phony behaviourist tries to address the barking and lunging without any thought for what is going on in the dogs mind

It is like going to a doctors with a compound fracture and the doctor putting a sticking plaster on it
You cant see the fracture so it must be fixed right?
It may still hurt like hell - but that dosent matter, its fixed
It may actually heal itself eventually - but that is very much not the best way to deal with the problem.

Lets think of it in terms of the dog

Most aggression is based in fear - if your dog really wanted to kill every other dog in the world he would not shout his intentions, he would be quiet and wait for his chance. Aggression is a warning, the dog is shouting 'get away from me!'

So the dog is most likely very scared

A phony will put the dog into a situation where they start to show aggression and then they punish the dog
They punish the dog harshly enough that the dog learns that barking gets punished and they stop barking

They are still scared of the other dog, they now have no way to tell anyone they are scared
And of course their poor owners dosent know any better and thinks their dog has now been 'fixed' from their 'naughty' behaviour and so they are safe to take everywhere - to be around lots and lots of dogs

So the dogs life has suddenly got lots more stressful.
Nothing is fixed  - it is just hidden

A true behaviourist will try and work to teach the dog that other dogs are good things, they will work at a distance where the dog dosent feel the need to shout at the other dogs
Over time the dog will learn to be happy around other dogs and will not need to bark
He will be able to be taken to lots of new places and he will be happy and calm with other dogs around.

Dont 'fix' the unwanted behaviour, treat the underlying mental issues and the behaviour will go away