My young shetland sheepdog does the same. Or, he is a master at balancing on his back legs, so he rather gives people "hugs". Rather soft and gently, and most people seem to like these friendly hugs. (At least as long as his paws are not dirty, ehm.)
But he is very big for being a sheltie so he must learn not to jump. However, my older sheltie behaved just like that when he was young. Now he is old and he never jumps.
If this dog is just a puppy or a youngster, I wouldn't make this a big deal. Wear jeans, yes. One thing I always do is grabbing the dog's paws or forelegs and hold them, just like I would shake a child's hands. Then I have control of the dog and can gently keep him from me a bit, and finally I can put him down, say "down!" and praise him a lot when he has all 4 paws on the ground. This assumes, however, that the dog is not the size of a Leonberger ...

As I believe strongly in positive enforcement, in dog training just like in piano playing

I think it is a much better idea to praise and reward the dog when he is doing something right, rather than waiting for him to do something wrong and say "no!" You can, if you are ambitious, bring some treats with you. Tell the family to command the dog to sit when you enter the house, and when he sits down, you greet him - totally ignore him before that - and give him a treat. If you do this often enough, the dog will associate your entrance with "here comes ... now I will sit, then I will get a treat!"
This is a very gently way of teaching the dog to behave nicely. You will be happy, the dog will be happy - after all, his only wish is to DO THE RIGHT THING, he just does not know that he is doing something wrong!
Now, imagine you are to teach a little child, who has never played the piano before. You put her on the piano bench, tell her to play ... she touches a key - and you give her a firm push and roar "NO! Not THAT key! You are doing it WRONG!"
That will teach her to play right and to love piano playing, sure? Well, most teachers are not that stupid to children, thank God. But dog trainers can do just like that and then they blame the DOG for "bad behaviour"!!!
So this poor dog thinks he is doing the right thing - a visitor comes, he greets the visitor as friendly as he can, to show what a good guy he is, and as everybody get excited and he gets a lot of attention, he must believe this is right. Next time he will happily do the same thing again. And then suddenly he gets an unfriendly push and someone yelling "NOOO!" to him - now what? What is he supposed to do now? So he desperately wags his tail to show that please, I AM a good guy, and he tries once more to get in physical contact, perhaps lick you in the face which also is his way of showing that he is friendly and inferior, because that is how a puppy greets his mother.
I guess that the command "no jumping" does not help much here, right? So, instead show him what to really do, what works, and he will do that. (And he will love you for the treat.) It will cost you humans some moments of work, because you will have to make an agreement, but still - the dog is just trying to be good.