Quite often you can spot an older tourist from the States a block away down in a big South America city. Bright white running shoes, quite often with a Nike swish. Shorts with pale legs and white socks tells you they just got off the plane. You can’t get a tan overnight. Tee shirt often with an American team logo. Camera and fanny pack. You can walk up and ask them if they are from the capitol of the state of their team logo and they’ll think you’re psychic.
Even in the tropics, older urban Latin American men generally wear black shoes with square or poiinted toes. They never wear shorts. Usually dark slacks or jeans, light colored short sleeve button down shirt with square cut worn out. Often with thin vertical stripes. Out in the countryside dress is regional.
The uniform of the younger gringo backpacker in city centers in Latin America down near the bus station is shorts, Teva sandals, a large backpack worn on the back with a smaller day pack worn backwards on their chest.
If you want to blend in with the locals and not stick out like a sore thumb, my advice is to dress more like the locals and less like a tourist.