I've heard 2 common examples of codom as it is correctly used in biology. Red & white spotted flowers is one. Roan cattle is another, where although the overall look is a "pink" cow, when you look closely, each individual hair is either red or white. So red & white both COexist, thus COdom.
I can't think of a single example of actual codominance in BPs, but somehow that is the term that gets used. If all the morphs we call "codom" actually were, then they'd all look like various versions of pied! Or they might have a speckled look because each scale is either color A or color B. Like lesser scales randomly distributed beside normal scales.
Honestly, a lot of the BP morphs don't fit terribly well in the definition of incomplete dominance. Pastel does. You have normal, then pastel (more yellows & blushing), then super pastel (lots more yellows & blushing). If you were shown a normal and a pastel, you could guess reasonably well what the super form looks like. Just like the transition from red to pink to white flowers. But some of the other morphs have super forms that really don't look like "even more of the same thing" the way super pastel does.
Which ties in to an explanation I often give when people ask how hets for a recessive trait can show through. Doesn't recessive mean there is no visible change in the het form? The problem is that dominant, recessive, incomplete dominant and codominant are words that humans made up to attempt to describe things they saw in nature. However, Mother Nature never agreed to play by those rules. The definitions do not perfectly describe all the variations that we see in nature.
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