I was trying to mount a tv support in the wall that separates the kitchen from the living room (from the living room side, and do note that the sink and the stove are on another wall, parallel to this one).
I checked with the Bosch gms120 that there wasn't anything wrong. It was yellow-ish, meaning that there could be metal traces or metal deep down in the wall. However, since I didn't need to drill very deep, I proceeded.
After a few millimeters, the drill started sounding like it hit some metal thing, so I stopped and checked.
Double checked with the detector, and still yellow, like there is almost nothing.
EDIT: Yellow and red are the colours displayed by the detector for "there may be some metal deep down" and "there is metal close, do not drill here". I live in Sweden, forgot to mention. The wallpaper is fibrous, not the wall, that seems to me concrete. On the other side of the wall there shouldn't be anything, I can't check since there is heavy furniture covering the wall in that spot.