I too always shower beforehand.
But that is just so that I am not a sweaty smelly boy.
It's baked into the time, and stated in most ads, that you will take a shower on arrival.
It isn't just for cleanliness, which is reason enough, but also so they can make final adjustments to the ambience of the room and the like.
You are correct in saying the time thing cuts both ways.
Either I'm lucky or choose well, because I always arrive a few mins early and send the 'I'm here please let me know when to come in' text.
Regularly the response to come in is a few minutes after the start time of the booking, and every worker just added the same amount of time at the end without either of us having to mention anything about it.
It's all swings and roundabouts.
I've found that if you are easy going, and show an ability to roll with the punches a little bit, I get the same energy in return and everything flows smoothly.
I'm not discounting that some people experience their time being cut short.
Or that the client is always at fault and therefore my attitude is the one true solution.
The one thing that I will say is that if you are seeing a worker or going to an establishment that is constantly shorting you to a degree that you notice, then vote with your wallet, go elsewhere.
Neither side of the SW/client dynamic should be taking the mickey.
