I have kids. 3 of them. A rambunctious bunch. We generally avoid taking them anywhere like our appointments, and in the rare case where we have no choice we bring distractions: Nintendo DS, books, etc. I know that not everyone has easy access to child care, and understand that.
It's amazing how many people come in thinking my staff and office supplies solely exist to keep their kids busy. Neither Dr. Pissy nor I see anyone under 18, so we don't keep kid stuff around.
I've seen people tell their kids to just go sit up by Mary's desk and play with her. Or give them scissors, crayons, and glue to "make something" out of the lobby magazines. Or ask me if they can play online games on my work computer. Or just let them run amok in my exam room with my stethoscope, hammer, tuning fork, whatever. Ed has been knocked over 3 times in the last year by kids.
I've had patients leave my practice because their kids caused trouble during the appointment, and I've told them they can't return unless they find a sitter. I don't care that it pisses them off. I can't treat you effectively if I'm chasing your child all over because you think it's my job.
In a pediatrics office this is more common, and they are prepared for it. I go to my kids' appointments, and they have all sorts of books and toys to keep them busy (but we still bring Nintendos). But I don't see kids, and don't consider that something I should provide.
Unfortunately, this kind of behavior is common elsewhere. You see kids running wild, knocking stuff off grocery shelves. I know a veterinarian who had a kid, with his parent's permission, urinate on his office floor, and the family thought the vet was being unreasonable to ask them to clean it up. They figured a vet would be used to dogs and cats doing that, so what's the big deal if they let their kid do it?
Although frequently told by patients under these circumstances that "you obviously don't like kids," that's not the issue.
The problem is parents who won't control them.