The moment that Amazon not only blocked my account from ordering after some payment hiccups, but also that of my girlfriend, who was living at a different place at the time, was the moment I disabled my Amazon account completely.

I at the time also had a look into what I could find in the settings about what they still stored about me:
They still had my detailed order history dating back to 1996, when I first used the service to buy books, giving a nice, very personal overview about what topics I had been interested in over the decades.

This has been in 2011 already, so unfortunately nothing new.