Spraying a man is the same as spraying a woman - they have less curves to contend with which makes it easier but their hair can be an issue if your not prepared.
I find angling the gun slightly upwards blows the hairs out of the way for the solution to get to the skin.
IF the solution collects on the ends of the hairs, just leave it, do not try to dab it off etc as it will do no harm to the tan, where dabbing and blotting could cause issues from touching the skin.
Remember if the man is bald or has a bald spot this will need a spray too as he won't want a white bit giving away that his tan is not real.
I prefer to know the client before I tan them but I always talk to all clients on the phone to book in appointments and this will allow my 'gut instinct' a chance to kick in. So far I have had no weird calls or inquires and all gents have been lovely and they really listen to the pre & aftercare advice.
Make sure you take the normal precautions for all clients of someone knowing where you are, how long you expect to be and you have checked out where your going on google earth or a street view site (so you know where you can park and if there is any alleys etc.. you need to go down.
Heck I wax those parts so I really doubt that spraying them will be more odd - after all unlike waxing I don't touch their genitalia when spraying them 
