I trust TJ 99% ~ he doesn't mark inside, he uses the pee pads. He has been to my Mom's house and he never lifted his leg inside (outside is a different story).
....now Roxy is 0% trustable. She would mark in someone home (carpet) for sure. Both inside and outside. She can only be trusted in someone's house if they didn't have carpet and I put tons of pee pads around for her. And YES she has to 'mark' every new pad
I had a foster who needed to wear a BB for most of the time he had freedom in my home. I took it off when we would rest and watch TV and go to bed. I made 'make shift' belly bands myself using a fleece blanket, I found this to be the most comfortable for him, as cotton would rub on his back legs and it looked like it would hurt