@Background Pony #DCA6  
I completely agreed with you, while we don’t really know their official ages are, one of the writers did mentioned that Spike is a adult in pony years but a kid in dragon years.

@TheAmazingPeanuts  
Nobody knows his or her age, but what they said is fair. I personally think that he at his best does not seem any more grown up than any of the Crusaders at their best, and feel that any of the girls are closer to being grown up than he is, if just by a bit, based on how the show portrays them. That said, there’s the obvious factor of ponies and dragons aging differently, with different life-spans to consider, so it’s not as simple as “who was alive longer”, but I think that there’s no reasonable way to claim with confidence that he’s some guy in his late teens while the crusaders are eternally 12 or younger. In any way this totally ambiguous topic is viewed, they’re all still currently children and this wasn’t an unflattering portrayal of them.

@Background Pony #1A6D  
You don’t know his age.

This is what I’d like to see more of in the series… Spike hanging out with kids his age and having fun and enjoying the simple pleasures of childhood with children as children do. Instead, he signed his union card with a crayon and spent the first nine years of his life sorting books and mopping Twilight’s bathroom(s).