Not all academic fields are so subjective. In math, science, engineering, and so on, it's entirely normal to build a good or bad reputation based on the actual quality of your work.

(Full disclosure: about a year ago, I came to the conclusion that Zizek was full of shit, and that his main real skills were sounding profound, avoiding testable claims of any consequence, and getting other people to venerate him. I can't remember the specifics, though, so take this with the usual salt grain.)

He talks about a lot of stuff and offers his opinion, which I guess you should take with a grain of salt. His actual field of expertise is in Ideology, and there I believe he can offer quite a lot. Regarding him "sounding profound", I guess it must be because of the way continental philosophers construct sentences, and us not being able to relate to their terms.

If you thought he was bad, you should listen to someone like Derrida (he's dead btw).

Regarding Derrida, I think a lot of what he was writing about was the fundamental biases inherent in language and how people use it. To coax these out he had to write in a way as to not get stuck inside these biases and to reflect them back on themselves. Christian mystics and George Bataille wrote in this way.

Not that Derrida is necessarily a mystic, but I think when talking about the limits and inherent biases of language, straight, rational writing gets stuck in the same traps the writer is seeking to extricate himself from, both the post-modernists and mystical writers throughout history have dealt with this.

The bit of Derrida I read had a structural element to it, that added to the content.