This was way back in 1999, and I didn’t understand what the point of Amazon was… So I wrote in their comment box: “Your website is stupid. You should shut it down.”
Immediately afterward, I was convinced that they were somehow going to track me down and punish me for being a little jerk. Hahaha :)
And look at them now… CLEARLY my constructive criticism played a pivotal role in Amazon’s quest for success ;)