Responding to the replies in reverse order:
Louis and Dalachin - Around the turn of the century, I was traveling for work and had the opportunity to visit orchid greenhouses across the country. It wasn't too difficult to find high-quality orchids because I could select the plants in person.
Now, living in a remote area and traveling rarely, I rely on a different approach. My strategy is similar to the ones you've described, except that buying 25-50 seedlings hoping for a high-quality plant is quite costly. Normally I'll purchase a couple of flasks or large community pots (com-pots).
Estación seca, I've always assumed what you've described, and it's why I never buy previously flowered seedlings. Given the significant time and investment involved, I want the best breeding stock I can lay my hands on.
A specimen could indeed be a top-quality plant that the breeder initially chose to keep but later decided to sell. On the other hand, it could also be a lower-quality plant that, for whatever reason, didn't sell. A quick call to the seller should clarify this.
One possible reason a seller might grow select plants to specimen size only to sell is with an eye toward showing, or a chance at award.
Thanks for our replies.