A little over 10 years ago, we always played an interesting game with our crew. There were always a few who tried to bend the rules, dress in personal clothing, and mix with the passengers in public areas.
We could always spot them because they were not as well dressed as the passengers.
Now, a decade later, we play a similar game. We still have crew trying to wear personal clothing and mix with the passengers. But now the crew are generally better dressed than the passengers. It's even easier to spot them now.