My sis and I have the same light coffee and honey color. BUT she has thin lips and mine are plumber on the lower part. The question is why does dark red lipstick looks OK on her to go the office and on mine it makes me look slutty. We both have black straight hair by the way. Also what color should I use? I'm tired of pink and light color. I want some dark color which doesn't makes me appear slutty.

Is your skin color the same? If you take a liner and line the inside of your lower lip instead of the outside and line the outside of the upper lip it will help balance it out... I have black hair as well and a thin upper lip and a fuller lower lip and I find this helps a lot

Go to the Mac counter. Ask a professional how you look. The whole slut thing could be in your mind. People appear to be the same color but everyone has different undertones.