With these palms dying off so very fast, I can't see how they can possibly blame you. There's definitely something wrong with the plants or environment. Check in the crowns of the dead ones for any sign of palm weevils (they are really large, and can kill a huge palm very quickly - they devour the growing tip). I'd be inclined to visit the supplier's location to check out what he's got going on there - if you see any palms with the same symptoms, you're off the hook!
Cold air, drafts, sudden low humidity (from the outside air), chlorine fumes from the pool - all those things are bad for potted palms that have up until now lived in a humid, temperature controlled greenhouse. It's possible that just the air circulation problem is the key. You need to visit more often than once a week to get a handle on what's happening, though.
Also, what you noted at the beginning - the white, scaly looking stuff is most likely an insect infestation of some sort, but wouldn't account for the palms dying quite so fast. They may already be stressed from that, though. I'd spray them all with an insecticide treatment as soon as you get them - one of the sprays with Spinosad is a good, organic approved remedy. Do that before they're delivered. Maybe make the supplier keep the palms for a week or so before you take delivery? It's possible his handling of them before you got them has stressed them even more, on top of the transition from greenhouse to pool area. Can you make sure he delivers them on a warm day, not at 8am in a snowstorm?
I'd also ask your boss what kind of palms she had growing there for 10 years, and why they aren't still there? Did something kill them too? As Hetty mentioned, Kentia palms are finicky even in a good environment so you should probably try another type, one of the ones that will grow in the desert? Pygmy date palms? (although they're thorny so you'd be constantly having to prune off the thorns).
