[seanmcdirmid]

BS. I think the opposite happens a lot: the student tries to "be interested" in what is hot or has funding/an interested adviser, they wind up unhappy and ineffectual because its all just pretend.

When you get a job and really get paid; you can be flexible with what you work on. When you go get a PhD, you should have some idea of at least the area you are interested in, you can be flexible within that area, but you should at least have one.