Leaving jokes aside

I have a theory:
You can tell a lot about a person by the sort of jokes they laugh at.

At one level this may seem fairly obvious, but I'm not talking here about labelling people who laugh at dirty jokes as perverts and those who laugh at racist ones as fascists. My theory is that jokes can reveal a huge amount about the way someone thinks on a deep level.

Take my favourite joke, for example. Before I tell it I ought to explain that most people who hear it don't find it remotely funny. A select few, however, find it hilarious and giggle everytime they think about it for days upon end.

What do you call a fly without wings?
A walk.

Did you laugh? Maybe you did; maybe you didn't. The joke is, for me at least, a very visual one and I believe that it is mainly people with a strong visual mind who tend to find it most funny. Certainly when I told the joke recently
to my top A level set (which consists of some cry visual learners) a high proportion of them laughed, and a couple almost collapsed. The same
Joke told to a group of non-physicists, however, produced a much more muted reaction. Coincidence? Or could there be something to my theory? Do visual jokes appeal most to visual thinkers? Do Jokes that play upon words appeal more to auditory thinker?

On a final note, when someone first said "Sarcasm is the lowest form of wit" were they being sarcastic?