I have had a few flight and gate agents mention to me over many many years that this practice is occasionally done. As per other posts, I am clearly not the only one who had received this impression. Whether it is official AC policy and acknowledged is another story. I agree that it doesn't happen often. I am not yet convinced that it never occurs.

By the way: the tone of others' responses to my original post is awful. You would think that I've insulted your mother. It's just a company! Lighten up people.