what bizzaro said. class is whatever you want. i wear sandals all over the place and i rarely gel my hair. i know, i'm a bum. =P
clinic says shoes for guys, but i'm gonna wear some clogs from now on for comfort. =P it also depends on what module you're in. some chiefs are more strict than others. i'm in a chill one, so it's pretty laid back. when it gets hot, sometimes i don't even wear the white coat. you'll get a feel for the place and just go with the flow.