As a belated followup, I should observe that if you're playing "in C sharp minor" on the black keys, you're skipping notes 3, 6, and 7 of the scale... and those

As a belated followup, I should observe that if you're playing "in C sharp minor" on the black keys, you're skipping notes 3, 6, and 7 of the scale... and those are the only notes that differ between a minor scale and a major scale, making the "minor" designation completely meaningless.