Good customer service does not mean being a doormat or accepting poor treatment just to get the client. Good customer service requires effort on behalf of the client too.
Write as though someone who knows the rules will be reading your work. A good editor will pick these bad habits, and they are bad habits, up and call you out on them. It might be an idea to throw a few deliberate errors into your sample edit pages just to see if they spot them. If they do not bring them up, that should be an alarm.