Filthy Hans posted:

Siskel was fun, and he and Ebert were very competitive with each other, especially with trying to find out how the other was going to rate an upcoming movie. That way they could anticipate the other's arguments and opinions and undermine them to look smarter in the show. Siskel would apparently resort to clandestine measures to accomplish this, like hiding under a table to eavesdrop on Ebert.

It should also be mentioned that Siskel found Cable Guy to be funny, so he's alright in my book.