When we used to catch our puppy we would say a firm no and take her outside, because of this, as the OP asked, she would be sneaky and be very quiet and hide her indoor messes. We also tried the silent technique and eventually she just started going to the bathroom indoors in front of us again. Being that both techniques didn’t work for me I have no clue which is better lol. I’m curious to see what other folks say about this.