Usually the guys who ask if you're a clock watcher or say they don't want to visit clock watchers are the ones who are going to take the piss with our time so always a red flag to me and to be avoided.
Bookings of less than an hour, yes I'm going to be strict on time, if they want to be cheap then they are not getting my time for free.
I've had quite a few piss takers who book 30 mins and always try to overstay, in the end I stop seeing them as the mind fuck just isn't worth it.
I believe a lot depends on which area of the country you work too, I seem to be in an area populated by the 59mins and 59 seconds brigade
so I definitely feel that that has an effect on the way I deal with bookings.