I notice when the shop is crowded or if there is heated discussion going on the cut might not be as good as the barber tends to get a little distracted from the task at hand and get caught up in the barber shop banter....I usually avoid all of that since I try to be there as soon as he opens in the morning.I always find, big tip or not, once they're comfy with you, they start doing crappy work. Then you gotta start nitpicking.