As a dog trainer's dogs, my wonderful canines are held to a very high standard, and people are often taken aback by the fact that they are reactive. We work diligently on this problem, and it is very much 'under control.' My dogs will never be the kind of dogs to frolic merrily around with other dogs, much less invite such contact. They walk calmly past other dogs, even side-by-side, but will become what is commonly considered aggressive if approached in a forward manner by another dog, especially while they're on leash.
When I started training professionally, and only had my eldest dog, I was actually embarrassed by the fact that she wouldn't simply accept rude and forward behaviour from another dog, despite the fact that she is a meager 25 pounds, and many puppies outweigh her at only a few months of age. Having grown up with very social and lenient dogs, very forgiving of any untoward behaviour from dogs of any age or size, I was of the idea that, so long as intentions are good, exuberant behaviour is acceptable. Because it was my dog who was reacting "negatively," she was the problem; we were the problem.
It took me a while to change my perspective, to realize that a dog who doesn't appreciate forward behaviour and reacts in what is deemed an aggressive manner isn't the one who needs to change their behaviour. Instead, it is the adolescent dog who disregards any request for space in lieu of insisting on playing that needs to be taught a different way of greeting.
I will often try and relate dog behaviour to human behaviour when it's applicable, and this is one of those cases. Even disregarding the fact that you will never be outweighed by a two year old, how would you feel if random strangers were to greet you with giant hugs or kisses on your face, all completely unsolicited? These normal human behaviours may be perfectly acceptable during certain interactions between known individuals, but certainly not between strangers passing each other on the street. The recipient of this attention could react in any manner of ways, but making every attempt to distance themselves would definitely not be considered rude, aggressive or abnormal. Humans may not display the same behaviours, such as snapping or growling, but the situation is very similar. Would it make a difference to you if the person were "just being friendly?" Of course not! That behaviour, irrespective of intent, is unacceptable between strangers.
Some dogs will be more tolerant, but those who aren't shouldn't be considered problematic or ill-behaved. If you own an exuberant dog who wants to be everybody's best friend with every fibre of their being, save him the unpleasant surprise of being spurned for his rude behaviour, and work on bettering their greeting behaviour.
Good luck, and happy training!