I can't speak to the other horses because Pasos have always been my breed. But I did apprentice with a Paso Fino Natural Horsemanship trainer. So, I'll just assess Philip.
He is not a horse I would buy.
First, the neck is screaming at me. Then I read the add and see the bosal. Then I look at the other pics and see his hindquarters.
This is a horse who pushes into pressure. Some people who ride in bosals accidentally teach them to do it more. The rider is uncomfortable with his energy and has tried to just lock his head down like that's going to fix it. The muscle in his neck has been developed incorrectly from all this pulling (if you're used to Arabians, etc. it might look fine, but it's not natural for a Pasos conformation).
The second piece of evidence is his hindquarters, which are not under him in any of the photos, he's strung out behind. Again, it's not an issue with many other breeds standards, but this is not how he was made to move.
A Paso Finos gait comes from the hip bones - they form an equilateral triangle rather than an elongated triangle. The design provides more balance allowing the horse to focus more weight in the hind, and therefore under them. The gaits of the Paso are all based on the footfall of a walk, at varying levels of extension, rapidity, and forward speed.
So, I don't believe Philip would be a smooth ride. It's likely he trots.
Could that be fixed? It would take a lot of work and time. He would need to be rested long enough for that bad muscling to dissipate, hopefully on varied terrain encouraging him to flex and bend more, laterally.
He'd need to learn to give to soft pressure and in-hand work on his lateral flexibility.
He will definitely need help with his anxiety from poor handling and likely uncertain / uncomfortable riders.
Basically he needs to be restarted.
It seems like "bottom up" was meant to mean groundwork and restarting. Rather than jumping on (top down). It is weird phrasing though.
I also don't care for the way the poster wrote the add. The problems with the horse are leaking around the sides, but they refuse to just be honest about it.
Like: "Hasn't left the farm since" = premeditated excuse for why he won't get on the trailer when the potential buyer comes. They haven't worked on trailering at all of course.