Yeah most of it is behavior... Yes it's correctable however in some cases it hasn't been corrected, or it's been avoided...
Is just like the video on the blog today where the guy is teaching the horse a bad behavior. Most buyers don't want to buy a horse that has that behavior and most would rather take another that didn't need that corrected.
There are people that like a challenge though

Just like I'll probably never own a Mustang from a round-up... They are in gerenal not happy about you picking up thier hooves, mainly because that whole being born wild thing...