Yep there are a lot of things I have learned here that have caused me to change my mind. For one, I was originally planning on getting an Australian Shepherd or Miniature American Shepherd. Then I thought about getting a Pembroke Welsh Corgi. I learned a lot, though, and decided that a Papillon was a much better option for right now and my current living situation.
Also, I have changed my mind a lot on the issue of breeding dogs. A loooong long time ago, when I was a teenager, my mom had me convinced that getting a male and a female and selling puppies was an excellent way to save up for my college. I had every intention of buying some pups off Craigslist and becoming an uneducated and irresponsible BYB. I definitely have since realized what a huge responsibility breeding is. Also, after I started to learn more about breeding, I was originally of the mindset that only purebred titled show champions should ever be bred. Now though, I'm a lot more open minded about breeding mixed breeds, breeding mixed breed dogs for working purposes, creating new breeds, etc. Also, on the issue of working bred dogs, I used to think that any type of working dog breeder was peachy keen. I thought that breeding working dogs automatically meant that they were breeding responsibly, because how nice/novel is it that they're giving their working bred dogs jobs. I've since learned to be a lot more discriminating between working dog breeders as well as all other types of breeders as my standards for quality breeders rose and evolved.
Not a total 180 but I went from feeding high quality grain-free kibble to prey model raw. Also my training methods have evolved. Like CP, I too used to be a Dog Whisperer fan. I tried some of his methods early on and learned VERY QUICKLY that they did not work for me or my dog, lol! Ever since I've been a mostly "positive reinforcement" trainer with a little bit of the other quadrants mixed in. I did used to be a lot more "formal" with marking and rewards and everything, and have since become a much more "go with the flow" kind of trainer, but I think that's just me settling into my personal training style.