Anyone wearing a maintenance uniform and carrying a step-ladder could surely find a way in via an overly helpful victim.
Look like you belong and act confident and you can get nearly anywhere. Props help-- wear a high-vis vest and a hard hat, carry a tablet / folio / clipboard around an office, etc.
Confidence is the key, though.
You also have to fit a certain expected demographic.
Sadly, yes-- that's true. It's a game of playing to stereotypes, for sure.