"I will agree that all the people who don't know she's a "dark horse" yet think she's an "unknown nag" - as soon as she shows a previously unknown accomplishment, you will know the truth too ; )"
So no one knows she's a dark horse because she has no proven record (a prerequisite to being a dark horse), but when she finally shows us her "previously unknown accompoishment" then we'll know she is a dark horse. Hmmmm. I'm glad you made that clear.
I'll bet you're a fan of professor Irwin Corey http://www.irwincorey.org/routines.html
I've never heard of the Professor, and I never said "no one knows she's a dark horse" - at least ONE PERSON does (again, the definition of "dark horse" ; )