I loved reading this story about your sister, thanks for taking the time to post!
There's a fine line between "appearance shouldn't matter" -- and when it really does.
Your sister's situation was very much like one of my best friends -- she was an accountant at a prestigious firm that served businesses and wealthy clients.
We went shopping one day and went to the "business suit" section, telling me that her firm required employees to meet with an image consultant every 6 months, making sure everyone had an updated hairstyle, look (subtle but current makeup for women, etc.) and wardrobe.
The unfortunate truth is that people do indeed judge by appearance and a company wanting to sign a multi-million dollar account isn't going to do it with anyone who looks sloppy or outdated.
I'm sure dating is very much the same way. We know God looks at the heart, but we're still human, and we still get our first impressions by appearance.
One of the reasons I'm single is because I've fallen into a very "cozy and comfy" way of dressing due to a more relaxed work schedule (mainly joggers and t-shirts with my favorite animated characters,) so I can freely admit to being too lazy to attract someone.
Either that, or maybe I need to go to an anime convention to try to find a boyfriend...
But I wouldn't be cosplaying, so even then, I'd still be considered under-dressed.
