Quite a bit. Contractors are people too. Most want/need straight up information in order to be precise in their work. Personalities rarely come into play but if one is difficult, find another. No need in putting up with someone with a bad attitude. When you do find a contractor with the right skill-set needed for the job and is consistent, KEEP THEM! You might have to spend a little more but you'll sleep better at night and your client will thank you for it too.