He's fought villains in the dark, and he looks black almost. Often times when they do a slow-motion sequence, you find it hard to see him, too much action going on while in the darkness because his suit is too dark, and while in the dark, it's even darker. Example, when you see him trying to take down the guy with the splitting copies of himself all at once, I can't find him, there's the flashy yellow blur going around, but the Flash is dark. What's the point if you can't see him in action?
In the 4th episode, the beginning sequence, Flash takes down the guys on the truck, even at day time, you find it a little hard to spot the redness of the suit, and his colors look almost the same as the men he's trying to take down that I get confused...and then the red blur doesn't match his dark colors and looks awkward.