I can't say that duty-free sales have ever bothered me on any airline. But even if they did bother me, it'd be a very brief spell of bother. In fact, if I happen to catch the eye of the salesperson I might just shake my head, but if I'm reading or otherwise busy I don't always notice them at all. And they've certainly never woken me if I've been asleep.

I don't know how much money the airlines make out if it. Some I suppose or they wouldn't continue it. Most passengers (in my experience) aren't purchasers though.