I've always gotten comped stuff: Backlight went out, they replaced the keyboard part of the case (dents), iSight went out, they replaced a lot of worn keys, iPod was broken, it was replaced free. I'm a plain-looking dude with old equipment, I highly doubt the amount of effort put forth for my sake was to impress me personally.
Quote from your link: "doesn't that say something about the quality of your products"
I would say it the other way around, they got snippy so I got snippy.
I do think there is a relationship between how over worked the are, and how friendly they are. The Regent's St. store in London is mobbed whenever it's open, hence the poor treatment. The other store I've been to is in Stamford, CT. where my interactions have been much better - not as good as yours with getting comps, but certainly I left feeling happy.
This is too bad really, as the Regent's store is more of a flagship store, and that's where things should really be working.
Quote from your link: "doesn't that say something about the quality of your products"
You were snippy, they got snippy.