Ambiguous

My dress is either black or brown;
I really am not sure.
It’s covered, too, in polka dots,
A part of its allure.

When choosing shoes and jewelry
To match, I go with brown,
A choice I reaffirm in mirrors
Or when looking down.

Yet once I noticed someone else
Who wore the dress as well.
Her shoes were black and yes, it matched,
As far as I could tell.

I’ve had this problem just this once
But what it’s clarified
Is next time I won’t buy a dress
Ambiguously dyed.