I've learned that using the term "viejo" (old) to describe someone is rude. Back in the States, it isn't so. Old is old.
But more polite here is the term, "anciano," which sounds all the hell like "ancient." However, its correct translation is "elderly."
If one wanted to say "ancient," it would be "antiguo," which also translates: "antique." Personally, I think I'd rather be considered an antique. At least people pay good money to collect those.