How young is too young for a spa?

I spent the last week in the company of four young children, and had I told them that they had to get off the swing set/come off the beach/quit playing in the dirt to head for a treatment at the spot, I would have had an argument on my hands (and been outnumbered). Kids play, grown ups treat themselves to the spa, right? Not always.

Spas are seeing an increasing number of young customers, so much so that many are creating packages just for families or kids. Some have even created a separate spa to accommodate their newest customers. But is spa going really healthy for kids? It depends on who you talk to. Critics say that manicures, pedicures, and facials teach kids that life is all about looking good and takes away from crucial life lessons kids should be learning. Proponents say that many spas offer massages and other alternative therapies and teach kids the basics of good hygiene. (Can't that be taught with a toothbrush and nail clippers?)

Though my girls love to have their toes painted now and then, I won't be pulling them out of the sandbox anytime soon to visit a spa. What about you? How young is too young to visit a spa?