He announces his hand - do you believe him?

[ras52]

If someone says they have a specific hand, how do you go about deciding whether or not they're telling the truth?

Last night in a loose, friendly club NLHE cash game with 50c/50c blinds, UTG says, "I want to raise, but I don't know how much. I have two black aces." Various suggestions are made from around the table, and he raises $10 (20xBB!). It seems an absurd move if does have aces (he's very unlikely to get any action) and it also seems absurd if he doesn't (risking $10 to win $1). The player in question is not clueless, so it's not a naive "Ooh, aces!!!" play and is clearly intended to befuddle. And it did.

Where do you begin? What are the factors to consider if you want to assign a probability to the truth of a statement like this?