These people need an electrician...

He has a few things going on there. First, he wired both leads for one switch to the neutral and hot sides of an outlet. That's why the hair dryer completes the circuit when it is plugged in/turned on. The filament resistance will not allow enough current to pass to run the hair dryer. There were probably also other circuits in the box up at the light that got confused too. At this point he needs someone with a multimeter and a little common sense/logic to get things sorted.