This is true. Well, the same horse that had the fear issues needed some more indepth training. I worked with him on slowing down, bending and flexing, collecting, extending, balancing himself, etc...
I have never saddle broke a horse. I worked with a 3y/o Perch X TB gelding who was a wack job that hadn't been worked with very much at all. I pretty much had to start from scratch with him. I worked with him getting use to standing in cross ties, leading, basic ground manners, picking up feet, lunging, and desensitizing to fly spray, towels, etc..
I have worked with some OTTBs, but not really retraining. The horses I have worked with that were OTTBs had already started retraining. They didn't have the "run run run" mentality anymore, but other than that, they didn't know squat. Worked on bending and felxing, collecting, and just slowing down. All of that was under the supervision of an instructor though.
I guess I'm thinking that this would make a challenging project as long as I chose a quiet horse that I got along with. And as I said, I would definitley not be doing much without supervision and instruction for quite a while. I would rather choose a horse that had started some retraining and not taking one fresh off the track. I really doubt I would wind up doing that.