The ones in fuel pumps are the worst. In my town I make a point of avoiding any gas station that has sunk to that level, but they seem to be harder and harder to avoid especially when traveling.
YMMV but at least here in the southeast USA, the default GSTV signal can be turned off by pressing a combination on the 4 soft touch keys on the outside of the screen. If your buttons are like so,
1 | CONTENT | 5
2 | CONTENT | 6
3 | CONTENT | 7
4 | CONTENT | 8
try the sequence 5 6 5 . Here where I am at, that mutes the sound. Sometimes 7 8 7 also turns the screen off.
But! You need to put it back to screen on, sound on, or the staff will notice and you risk them changing the combination on you.