I doubt that they are profitable at all in the long run. They are typically bet down as you know.
Your play against or pass is probably as good as any.
Do understand that when these horses are bought as yearlings, while plenty of good info is out there, they have never had a saddle on their backs. Just like draft picks, no matter how much homework you do, it is never clear until it is too late. Because a trainer has plenty of time with the horses before they ever race, while they can't know everything about the horse, they DO know an awful lot. It is unreasonable to think that a trainer whose owner paid a lot of money for a horse, and that amount is published for all to see, would try and " steal" a race or risk losing a horse unless there was a very good reason.
It's not always about soundness. Maybe the horse just can't run. Big, strong, good looking, great temperament, no breathing problems, and can't outrun the pony. Just like people, it happens.
Any time JBEX.