I AM sure it's my bra that sets it off. I do not wear pants with rivets on them (which would be near the walls of the WTMD), and most of my pants have nylon teeth on the zippers, and just metal pull and stop. And then a hook/eye in metal, or two. To put it politely, my bra size does not correspond to a letter grade you can get in school.

I take off my watch, earrings and necklace (and put INSIDE a carry-on bag), and I don't wear rings. I have pre-emptively gone through 'sideways' saying that it was so my bra didn't set it off, and they didn't seem concern. I've also tried to go sideways the 2nd time through, but that time it didn't help.

I had an Aunt tell me (about 10 years ago) that if you hold your hands together in front of you (i.e., away from the walls) you had a lesser chance of your watch/rings setting off the WTMD.

I've also been told that the individual airports have no control over the sensitivity of the WTMD. Though I'm not sure how much I believe this.