I think one of my biggest issues with professionalism is people needing to be paid RIGHT NOW once a job is complete.
Send me a bill, dammit. Some subs are like this.
We always send a bill, if there are any issues or such we will address them. It gives everything a few days to sink in and make sure the customer is happy.
Nothing pisses me off more than the expecting me to go out of my way or meet them there with a check the second they are finished. Seems pretty unprofessional to me.