Is It Difficult to Identify Prostitutes?

Allow me to clarify this slightly concerning title by confirming that I have never requested the services, or indeed provided the services, that a sunset operative is best known for providing.
But how do you know, if you are attempting to procure this form of support, how do you know that the person is actually a prostitute?
I traveled to London last week and as a result was driving around Hull at 5am, a time of day that reaffirms the fact that Hull is a city that sleeps. It might be all fine for somewhere like New York to "never sleep", but in Old Hull we are so busy that we just need to nap from time to time.
Whilst driving to the train station, I passed  a female, perhaps in her mid-twenties, wearing dark trousers, and a padded blue jacket. Now she was stood down a street waiting for something. But I've no idea if she was a gigolo or not. She wasn't wearing a leather mini skirt or basque (is that the right word - apologies if I have offended any folk of the ethnic grouping located in Spain and France by suggesting that workers of ill repute may wear you) but then it is 5am in mid-October, slightly misty and definitely not weather that you would want to be out in without some good quality garments.
But what if she was just going to work somewhere that was a long distance away and she was waiting for a pre-arranged lift? As a man who, on a good day can vaguely resemble an out-of-shape lumberjack, I am aware of my potential to worry vulnerable females - little do they know that all they need to do in my case is brandish a mouldy peach and I will scream like a little girl - and, if I were attempting to hire a night person, what if I approached her with an offer to purchase her and she wasn't one? It could be a very uncomfortable conversation...  "Hello there!" I would cheerfully announce.  "Um, hello?" she might respond.  I could attempt to identify her by asking "Are you working?"  "Well, I will be when I get to work."  "Work eh? A nod's as good as a wink to a blind horse! In you get.  I'll take you to work! Rowr!"  "Are you a curb crawler?!? I'm calling the police!"
And vice versa - what if I stopped, offered her a lift to the station, thinking her not to be a prostitute, but she actually is, so she gets in the car and is very displeased when I actually drive to the train station, and politely indicate that she leaves the car while I get a parking ticket? She might follow me onto the train thinking it some kind of bizarre role play, only to kick up quite a fuss when I refuse to pay for her ticket and the conductor throws her off at the next stop.
Maybe I shouldn't be up this early.
If you're still reading, I urge you to check out the video below, of one of the epic fight scenes from The Matrix series being re-enacted in Macy's.  It's great!