Who knows! But note that all the shirts are buttoned as men’s shirts should be buttoned. So it’s not a matter that anybody mirrored the image in Photoshop so that OHIO would seem to be spelled backward.
Found a discussion from 2008 that confirmed that Obama is (1) Left-handed, and (2) wears his watch on his left-wrist.
I’m a lefty and I wear my watch on my right wrist. Wearing it on your “off-hand” is the accepted thing, but on that discussion threat a lot of other left-handers claimed that they did the same thing.
I dont’ know if this is a left-hander’s ‘thing’ but I generally notice quickly if a person is right-handed or left-handed. Maybe it’s from having played a lot of pick-up basketball?