I have the disallow problem. When "disallow" is on, I'll get a lull in business during off hours, but during peak meal times, they just keep on coming so I have to close and lose the profits from those who were still in the middle of their meals.
Also, my customers in restaurants, whether it's my place or I'm just visiting, get up to eat and drink and wander to talk to people at other tables, so at times, I've got entire gangs of people just standing there chatting with each other and sometimes eating.
Those are the only two problems I've run into so far.