Hey, to each their own. As for my GS, they've been "joyous and sprightly". I like that they *can* be serious - but they are still basically joyous and light-hearted. I don't like endless goofiness in dogs any more than I like it in humans (1 of my cousins is an example - can he *ever* be serious? *Constant* [and I mean that] joking around eventually makes me want to puke!).
Of course, 1 of the Labs across the street is quite serious - he's dog-aggressive and a better watchdog for us than our current GS!
My dog can turn it on and off -- this morning when the workmen came to see about the deck she was dashing from man to man, bounding and wagging, until I whistled her to "heel" and "stay". Then she sat alert, watching everybody (but with the tip of her tail still twitching in a vestigial wag). And of course if I had let her go she would have started bounding and wagging again . . . but if you show her a duck, she's all business.