In the music I teach, unlike what dannye played, long fingernails are the bad career move.

I must make the speech, only to women, of course, that elegant nails and piano playing do not go together. But it isn't only women who have the "castanets"--anyone whose fingernails strike the keys when the lowest joint is vertical...will CLICK. And it will collapse.

I encourage all my students to have firm fingertips, not exactly finger picking, but feeling as if they're lifting the piano keys up. It is quite counterintuitive.

Think about it! If the nail prevents the finger from being firm, there is no sturdy connection. And the control all musicians strive for, will be lacking.