The use of the color is quite different from a regular character, so measuring by the same yardstick makes no sense. This is a blob of color, not just some thin lines.
> these bizarre characters
At least on Twitter.com, they're not characters, they're SVG images.
At first, I was thinking that I could see the difference quite clearly between the two colors and I had no clue what you were talking about. Then I hit the "swap colors" button and happened to notice that there was a bunch of text on the left side that I hadn't even seen...