I'm not sure who told you that the colors are not hereditary, but I disagree.
I feel that the colors and patterns are (genetically speaking) very potent.
Pattern variations ("morphs" as some call them) and colors seem to be polygenic in Cresteds, meaning that many genetic factors contribute to the appearance of their offspring. You just have to get an understanding of how these variations work.
Without writing a book, I will try to show you a little of what I've seen over the last year or so. This is by no means a large enough control group to constitute a scientific study, but still interesting.
I'll break it down into two sections...one for color and one for pattern.
Color
While you may not get babies the same color as two like colored parents, there's still a method to the madness...you just have to try to understand how the colors work and what they mean.
I'll use my line of orange cresteds as an example of how color can work...
When I breed two of my oranges together, I often get babies that are more red than the parents. My theory is that the brighter or more reddish color of the babies is due to the fact that the parents are predisposed to two things...
1. Having less yellow pigment
2. Having more red pigment
So in a nutshell, when I breed two of those oranges together, I'm basically pairing up two geckos that both have a genetic predisposition toward more red and less yellow...which makes for babies that end up with even more red and even less yellow.
Dad

Mom

Baby(at 4 months)

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OK...maybe this is a book...now for section 2. 
Pattern
With pattern, it seems to be more variable than color. The pairing shown above has produced Tigers (just like the dad), Dalmatians (just like the mom), some Tigers with Dalmatian spots and some "in-betweens" like the baby shown, which show just a little of both.
In addition to getting a mix from both, it seems that some pattern traits work in a recessive fashion, meaning that you can occasionally get a totally patternless baby from two patterned parents.
To show you what I mean, here is another pairing and two of their resulting offspring.
Dad(Same male as above, but different female)

Mom

Baby #1

This one has the father's orange base color and tiger pattern very strongly on its sides, but it also has the mother's orange flame pattern on it's back.
It should be noted that the majority of the babies from this particlar pairing look like this, which tells me that both the Tiger and Dalmatian traits are of a dominant nature.
On the opposite end of the spectrum, we have this...
Baby #2

This one, as you can see, is completely patternless...which to me, means that a recessive gene for patternless is at work. In other words, my theory is that the father (a tiger) and the mother (a fire) are both "het" for patternless. This is the only patternless baby to hatch this year from this particular pairing.
A note on this ones color...this one is the same color as the mother's base color was at that age, meaning this gecko will most likely be a burgundy/red color as it gets older.
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Like I said, this is far from conclusive, but should give you an idea of how color and pattern works.

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Anthony Caponetto
www.ACreptiles.com