How do you figure out what a light switch controls?

There is a light switch in our house whose purpose we have not determined. The switch is near the entrance to our living room, so we figure that it should control something in the living room. There is no ceiling light fixture and we have tested all the wall outlets in the room by flipping the light switch with a... show more There is a light switch in our house whose purpose we have not determined. The switch is near the entrance to our living room, so we figure that it should control something in the living room. There is no ceiling light fixture and we have tested all the wall outlets in the room by flipping the light switch with a lamp plugged into all the outlets, one at a time, but the switch has no effect - the outlets are all always on. For those of you who are wondering whether the switch is actually wired, it is. Is is possible to determine what the switch is meant to control, without calling an electrician to come tell us? If so, how?
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