It matters less what you wear than the fact it's clean and odour free! Training with someone whose kit stinks of stale sweat is plain disrespectful and disgusting. It's not about looking smart as much as looking workmanlike and dare I say 'professional'. Turning up in shorts that are ripped and dirty and may show more than you intend is also unpleasant for other students, wearing t shirts with dubious slogans on is also disrespectful. Turning up clean and tidy, nails clipped, hands and feet also clean is the best way to come for training.