The problem is that it's very hard to differentiate the dance/sport variety from the fighting variety. Oh, yes, you can tell after a few visits to the individual school, but, when a school calls itself a TKD school and wants to train for real self-defence, it may be seen as part of the larger dance variety.
Not if you treat searching for a reputable school as has been soooooooo many times on this board, interview the head instuctor/owner of the school! Ask the pertinent questions, what are your qualifications? What is your focus (competition/SD)? Watch mutiple classes for a couple of weeks so you REALLY see what is being taught. Talk to existing students! If there's a very high children student body, chances are they are geared toward a softer training regimen. Use common sense thats all!