Neither of my dogs will show enthusiasm to strangers, none at all. Even Delgado who is extremely food driven will take a treat politely and then look away not interested in more from them.
For people they know at home, they show enthusiasm but that doesn't involve behaving like lunatics! It means wagging tails, licks, and for Delgado grabbing one of his toys and offering it to the person and finagling a fetch session.
Personally I don't see having manners as a bad thing either
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 5 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010