This is a tricky one, I'm not sure I've ever been asked this question EXACTLY, but certainly a variation of it...
It's quite an easy one to divert if you are a bubbly warm person...
I answer something along the lines of "do you know, the most attractive thing on any man is confidence and presence. I've been attracted to all kinds of men,never really had a type, which is why this job is perfect for me because I meet so many different types of people."
I think it makes them think they asked WHAT you find attractive, and if they still don't think their question that was asked was answered, I replied so happily and confidently, and also reminded them how many different types of people you do meet, they probably feel less inclined to ask the initial question again.
Sorry, I think I know what I mean there but just read it back and might sound like gobbledygook!