An OTTB may one day be a nice hack.. but it usually takes a good lot of time and training.
I "broke" and trained more than a few horses.. and rescued a few.. and I learned that it takes as much effort to take a good one as one with issues (conformation or soundness). Pick your battles (or training prospects) wisely!
Ultimately, if a horse has possible soundness issues coupled with conformation issues, you put all the effort in one end and don't get much out the other end. It costs as much to keep and train a good one as a not so good one.. choose good ones.
And.. remember.. advice is worth what you pay. ;)