Other people... in general
Sidewalk seating is typically a small fraction of the total seating in a restaurant. Thus, you are often crammed in there, along with all 15 other smelly, sweaty, Acqua di Gio-covered people with farmer's tans covered in mosquito bites and spray-deodorant, crammed into a tiny, fenced off area with 15 puggles!
On the plus side, the close proximity to other diners is great for eavesdropping on people's crumbling relationships. But it's not the best way to enjoy the company of a friend, a family member, or the person you're breaking up with in public because you're worried they'd throw something at you if you did it in private. I'm speaking in general, here. You know where you don't have to overhear that balding rich guy's divorce proceedings? Say it with me... oh, you know where.
Lee Breslouer is a senior staff writer for Thrillist and enjoys a cold blast of air conditioning all summer long. Follow him to first-world complaints at: @LeeBreslouer.