Denimgirl, it’s not about “showing the real you”. It’s about showing respect for the person you are meeting for the first time. “Showing the real you” on a first date gives the impression that you’re more interested in yourself than in your potential zivug. I doubt that anyone searching for a prospective mate would find such an attitude endearing.
There are, of course, dating occasions when casual dress, or even rough dress, may be appopriate. A first meeting isn’t one of them.