I know the following answer is not going to be popular, but let me vent out for a moment how I feel.
According to the usual page, the site is for:
- practice & performance technique;
- music theory, notation, history, or composition;
- technical analysis of a specific, complete work, or well defined section thereof;
- instrument maintenance; usage of specific music software or hardware
Music stuff, in brief.
Now, I feel that "yo my friend does not know music but wants to play songs on his Casio, suggest a book" is not music stuff.
IMHO, it gets off topic exactly at word 8: "but".
"But" as in, "my friend does not know music and does not want to learn music but...".
"But", not "and", as in "I am a 40-something, I do not know music and I want to start learning, how do I weed out the bad teachers from the good?".
Same for "I do not know music but I want to play at a wedding", "I do not know music but I want to learn some songs on the piano", and all that.
I mean, okay, fine, good for you, if you can manage it you might go on TV as "the guy who can sight-play Ravel and does not know music" but the whole premise makes the question less than worthless, IMHO.
Not only I don't think they can add anything to the site (because you can't answer that seriously except with "Wanna play Fur Elise? Good, start taking lessons, see you in 5 years") but also because they are off topic, non-musical in their nature.
I think those are a prime candidate for closure, much, much more than "I am a classical player and I want to learn jazz, where do I start" even if technically training a chimpanzee to play piano would qualify as "practice and performance technique".
There, I said it.