Last week I had a stinking cold, but like I say I was able to perform my sports workouts so would have felt a bit unfair to cancel everything else. What I did do was inform my clients at time of confirmation. All said they were quite happy to go through with their bookings. One who saw me on my worst day informs me today, which is over 4 days since that he has not contracted my cold despite two hours snogging-and other sexual contact.
I've seen other clients at other times when I've had a cold, some catch it, some don't. All are fine about it, a few do cancel sometimes but it's their choice which is the important bit(and my choice to carry on OR take time off).