For some reason I've just wondered whether it's the same the other way around. Punter with poor illegible messages = slightly odd = good sex?
Perhaps one of our resident SP's have a view?
I know what I think but it's just a guess and I may be wrong.
No but poor communication can indicate he is going to be difficult, a good client is someone who is easy to make arrangements with, communicates well, provides relevant and requested information, confirms as and when requested. Turns up, has a good time. Isn't pushy or indiscrete at any point, has the correct fee...I could go on. When I say communicates well, this is not about grammar, spelling, flounce it's about providing useful, accurate information easily.
Sometimes poor communication improves after the first booking, sometimes it doesn't. I have had clients who have been great in the booking, but difficult with communication and unreliable. There is a limit and if the messing around reaches a certain amount, I will stop accepting bookings no matter how wonderful he is in the booking. Similarly if someone is pushy, unpleasant in a booking, doesn't matter how reliable and easy to make arrangements he is, he will be banned. A good, bad or otherwise client for me is based on the entire interaction from booking through to aftermath.
'Good sex' is subjective and not the primary objective.