I was trying to hang my TV at my new place, on an interior wall (between living room and a bathroom). Using the stud finder on other walls worked fine, but on this wall I got some very strange readings. An area of about 5 feet by 4 feet was setting off the AC warning, and studs seemed to be upto a foot wide and at irregular spacings.
I ended up drilling "exploratory holes" looking for the stud, because it didn't make sense that there would be tens of power cables in the walls, equally spread between the studs (in the air space between, and the ones attached to the studs shouldn't be within a 1/2" of the drywall. The studs turned out to be simply 2x4s with 16" centers.
Is there a trick I could have used rather than just drilling into the wall in exasperation?