I have to agree, the tan is my least favorite color in the cowl. It has some pink undertones, so it reminds me a bit of the "flesh" crayola crayon.
HOWEVER, I have shown the cowl to a number of knitting friends who wear colors in this range. Most of them were worried about my choice of the bright coral (this was before I had finished the cowl). All of these same knitters like the color progression and all the colors in the final result (to the point that a number of them have hinted that if I want to give it away, they want to be first in line to receive it).
In part, I chose these colors for this color blending project because I had no idea WHAT I could possibly use these particular miniskeins for. I figured the resulting cowl would work as a gift or charity project, and either way, the yarn would be out of my stash in a guilt free manner.
I did several combos before deciding to use my least favorite yarns. The other combos fit my personal color taste much more, and will probably be turned into cowls before year end (the top group in this photo is what I used):