Please don't share your talents

I've never really been one of those people that likes to just sit down and start playing on any piano I see. But, I also don't really mind hearing people plunk out "Heart and Soul" or whatever (I've spent too many hours practicing the same notes over and over; slow, fast, with and without pedal, again and again and again, to think that music should always be "performance-quality"). However: occasionally, when I was trying to do my homework in the Wilkinson Center at BYU, or when I was sitting in church waiting for Young Women's to start, I wished someone would put up a note like this:

(from here)