Lets see, I find this interesting because this "mistaken identity" affects my day to day work.
I design fire suppression sprinkler systems for a living. Many of the projects I work on are in tenant spaces in buildings being remodeled. New walls and ceiling etc. Anyway, there needs to be a little field survey work done in these spaces in order to prepare my drawings. So I have to run around the loop here in chicago to a bunch of buildings. This allows me to ride my bike during the day, going from building to building. The problem I was having, was walking up into the dock and then trying to gain access to these buildings and projects I am working and being told what I want to do isn't allowed by messangers, becasue the dock guard / Service guys think I am a messanger. Rightfully so, I walk up with my helmet, rolled up jeans, cycling cap and a messenger bag, what would you think. So now when I lock up my bike the helmet stays with the bike, steel toes get put on, hard hat gets worn, cycling cap comes off and jeans get rolled down. I just found it interesting those first few times that no matter how many times I told them I wasn't a messanger and was working with so and so contractor in the building, on such and such floor, they still would have trouble believing me.