Toward More Colorful Language

Sometimes, an author doesn't give as much description as I'd like.  Other authors go on and on about something that couldn't possibly interest anyone but the author (and, apparently, the editor).  Here's an example where the author tried, but it left me with a lot to imagine.  From The Borrower by Rebecca Makkai:

And the way he would show up just like this, flashing his piano-key teeth.

Are his teeth yellow?  (My grandmother's piano was so old, it had ivory keys, and they had aged to yellow.)  Do they have black spaces in between them?