I worked for a barn that had black and yellow as the barn colors. I never thought it looked like a trash bag! But then I was used to everything being those colors. Along as you get the trim in red it should look fine.
I just got one of these to use at shows when we have to walk back and forth from the barns & rings in the rain (I love being in charge of our club's year end awards and can pick out my own award!!). I also chose a black one for someone else and did silver lettering/embroidery on it and liked it in that color. To me, they just look like a nylon sheet: