He's a cutie! I've always felt (with no empirical basis) that adopted dogs know they were saved and therefore are "good boys/girls" as a matter of thankfulness. No offense to those that chose to buy a dog but I am so thankful when people adopt a mutt.
I don't necessarily disagree with that thought, but we had 2 Golden Retrievers previous to these guys and they were fantastic goofballs. We lucked out in both cases, the first failed his last living assisted test and they needed a home for him. My wife worked with a lady who was a trainer and hooked us up. All we did was make a donation to the facility. The 2nd was a non pro breeder, more if it happens oh well. We picked him up for $500 and a 4 hour drive. I think it depends on the breeder and breeding situation, as in too much in breeding, as to the dogs behavior to an extent. That being said we couldn't be happier with these guys and are happy we helped them out.
I think the vast majority of dogs are good boys and girls, regardless of adoption status, as long as they are treated properly.
I am sure you are correct but it seems to me when a dog is removed from a bad situation such as a dog pound or standing on the side of a road after being dumped they seem to know things have improved for them and appreciate it. I've never bought a dog so my feeling is pure speculation.
Every animal is different, much like humans are. Not as complex, or intelligent, but certainly different. Bad experiences leave a mark on them and the human working with them needs to know what they are doing to counter that. It applies to cats and it applies to dogs even more.