I personally am a "Scratch" baker. I wonder how many of the doctored mix users clients know that's what they are using??? Or know enough to ask. And if they find this out, how ok are they with this?
I know that in the end if the client is happy that's all that counts and that there is more to a cake than the cake it self. You can have a wonderful tasting cake and it look like crap because the decorating is lacking. So, I guess it's six to one half dozen of the other. I understand each person is different and that's what makes the world go round. So, not trying to offend anyone.
A couple of good books to check out at your local library are, "The Art of the Cake:Modern French Baking and Decorating" by Bruce Healy and Paul Bugat
"The Cake Bible" by Rose Levy Beranbaum