The mistake is this: you've not answered the question "professional to whom?" Instead, you're substituting your own definition, augmented by the opinions of semi-random strangers. Now having a strong sense of professionalism and values is a Very Good Thing, but when you're taking someone else's money, you need to work to their definition. (If you don't agree with and can't abide their definition of "professionalism", don't take the job.)

It may be a little late in the game for you to ask, but have you determined what the people on the other end of the contract consider to be a "professional job"? If they're big on written doc, focus there. If they're big on unit tests, focus there. You get the idea.

(Update: On re-read, my tone may be a bit condescending. Not my intent. This particular mistake is one I have lots of first-hand experience with. --dws)