For sincerity, try a dictionary

Simon Cataudo | stock.xchng

I've heard the one about "sincere" meaning "without wax" several times now, but I ran it through Google anyway, just to see what happened.

Oddly enough, it turns up in Dan Brown's novel Digital Fortress, which was published in 2008. Now I'm striving to remember whether I heard the "without wax" story before then. I don't think I did.

It has that pseudo-real factoid feeling Brown so well known for. He puts his version in a paragraph of pure exposition that any sensible editor would have struck and labeled "telling." He also sets his version in Spain, while the usual setting is ancient Rome. The standard version (and there are many) goes something like this:

Marble merchants used to disguise flaws in the marble by filling  them with wax. So honest marble merchants would advertise their wares as being "sine cera" -- without wax.

However, as even an Elementary Latin Dictionary can tell you, "sincere" is itself a Latin word meaning -- brace yourselves -- "honesty." It's probably related to "sincerus," which means "pure" or "entire."

Any good dictionary will give you the proper history of a word, so consider looking things up before including spurious folk etymologies in your article, speech, or novel.