Think of it this way... man I wish I had a link, I'll just have to paraphrase.
Question: How do you define pornograph?
Answer: I don't know, but I'll know it when I see it!
I was just cautioning that the user may think they like something or that they ought to like something based on some idea of their self image or whatever, but it might be more useful to put stuff in front of the user that you think they'll want, and they can choose to axe it and you can make a better guess next time.
Meanwhile, the user is still free to peruse content to locate stuff they want without forcing them to surrender a preference a priori.
The downside is the user may not get a chance to say they like a thing because it was never put in front of them, especially if the raw signal is such a firehose that they drown whenever they go off on their own.
Part of the problem is that we can never know all of what is being created, all we can do is provide ourselves the best opportunity to be exposed to things that we are likely to want.
And I think we're now starting to converge on the same idea.