Welcome the the forum, Isabelle.
As you do your research you may want to read some of the threads on the trainer you are interested in (just do a site search)
Another thread to read that explains some of the problems with aversive training methods is here https://www.dogforum.com/dog-training...-fallout-4776/
This forum is full of folks who are big fans of positive reinforcement training. I think learning about that method will further enlighten you in your research.
Here is a place to learn the basics YouTube - kikopup's Channel
And just one more caution. Around here the topic of the dog whisperer seems to cause passionate response and usually threads end badly. So perhaps the best thing for you... so you don't end up in the middle of another storm here, first thing when you join!... is to read up on the suggested threads. Then if you want to discuss him, perhaps start with a few private messages to folks here. You'll get to know us and know who to ask different questions!
Another way to approach this might be to ask a question about a specific training method, but keep the trainer's name out of it. I know this sounds strange, but as soon as we say his name around here, things sorta go crazy.
Again, welcome. I hope you enjoy yourself here. Folks are very helpful and eager to pass on what they have learned here.