Just to add my own odd data point to this question:

Wanted to book F class YVR-JFK on Cathay. BA showed 0 seats on the day I was interested in. On a lurk I checked Asiamiles.com to see if they showed any availability and they did. So I tried calling Alaska. They were able to see the seat, book it, and I have a confirmed ticketed reservation even though BA was showing 0 seats.

First time I've seen THAT happen! But I LIKE it!