@seven Tell your friend the small licks of puppy / dog will be less harmful than a handshake with other human.
A lick of his nose by dog is just it's way of showing how much it loves him.
Quite frankly the licking their stuff isn't as common as it is made out to be. Licking is the only way they can keep themselves clean but if from puppyhood a dog has been cleaned with a towel chances are it won't bother licking it's stuff.
I say this with experience of raising Magic for past 7+ years and he mostly just concentrates on his paws - a pawdicure if you like.