I’ll start… someone has to : )
No T-shirt, no sticker, nothing, on my side. I never know before when I’m going to map things, I tend to improvise.
Usually, to have acceptable sequences, I decide at the beginning of my mapping session a number of step to walk between each pictures. Depending on the subject it is usually 3 steps, 5 steps or 10 steps. So I walk, counting the steps, I stop, I aim and I wait as (reasonably) long as someone appears on my screen before shooting. If the area is crowded, I stand in a way that makes obvious I’m waiting for the conditions to be met to take a picture. Two reasons for this: privacy and quality of the resulting document. But this takes long.
Of course, seeing someone doing this makes some peoples to wonder what I’m doing. Most of the time they think I’m just willing to take landscape pictures (which is true) so that’s no problem and I have no questions. A couple of times though I was (kindly) asked was I was doing. I just explained I was documenting the area, which was satisfactory to those who asked. And when by accident someone appears close on my screen while I’m shooting, I just tell without being asked that either I’ll take another one or I’ll blur this person’s face. This is obviously sufficient as I never received bad comments. Just things like “don’t worry this is no problem”, “ah, OK, thanks” or a smile.
I also tend to map special events like festivals or outdoor gigs. In these case I’m just unnoticed, or if I am, this is by attendees who jump in front of the camera, smiling. So no problem here too (but doing the blurring right after, which takes horribly long : ) ). And when the special event consists in a city or street condition (garbage collectors strike, flood…), people tend to think I’m working for the district or for some administration (I was told that two or three times). In such cases I just reply I’m doing this on my own to document and keep track of these events, and I add this is going to be published on a website.