I've no intention of logging back in to check my notification settings, but when I was using Facebook, I would get a push notification maybe once or twice every couple of days. Now, I get more than a dozen SMS messages a day.
I've built notification systems in the past, and in every instance, respecting the fact that abusing the notification power entrusted to us by our customers was seen as a cardinal sin. Maybe it's the absence of that respect that has catapulted Facebook to where it is, or the presence of it that's held me back in my own endeavors, I don't know, but man, as the recipient of all this spam, it really, really feels unsavory, and further evaporates whatever trust I might have had in the platform.