The last time I was in Times Square on New Years for the ball drop which was 5 years ago now I did see a few people who were wearing adult diapers while waiting for the ball drop.
The persons shirt rode up and I could clearly see the diaper sticking out as well as see the diaper bulge in the persons pants.
When a diaper has been wet you can see it pushing against the persons pants if you look close enough but most people would not be aware or care if someone is wearing a diaper.
I have a good bladder so I just held in my pee and waited to use the restroom after the ball drop in Times Square was over.
Of course toddlers and babies and possibly younger children were in diapers including my 2 and 3 year old boys they were in diapers at Times Square when they were with me because they were in diapers all the time anyway because they were not potty trained.