Using the phrase when trying to sell a Pied or a Sunglow is fine. Both morphs are highly recognizable. A piebald is generally priced by the level of white it displays and so pricing a high white piebald at $8-10,000 and stating "Pics speak for themselves" is fine because the potential buyer can easily see that the price is justifiable (at least to some degree).
With color morphs (pastels, yellow bellies, etc) the phrase shouldn't be used at all (in my opinion) unless the animal is very clearly a shining example of the morph. Why? I've seen far too many pics where the lighting was poorly setup that distort the true color of the animal. Sometimes this is intentional and we see ads for normal animals that someone is attempting to pass off as a pastel.
I still wonder if people who are selling their "next big thing" balls for $1299.95 (ACT FAST!) realize how transparent they are being. Obviously they bought the animal as an import or at a pet store for under $100. Apparently, according to their ads, these are "simply stunning" animals in person, but I guess I'll never know.
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Sometimes, things are exactly as they appear...sometimes.