Answer:
Scoliosis can be very obvious, or not. I depends on the angle of the spine. Some mild cases don't affect the person very much at all. I am braced for scoliosis, but when mine was first discovered, it was during a sports physical and I didn't even know I had it.
Some people, however, have a very large curve and it is noticeable. It effects the way they look, stand, and walk.