Listen, I hate Clemens more than anybody, but after reading this, I think I have to say that the guy is clean.

http://www.sabernomics.com/sabernomics/index.php/2008/01/what-do-the-statistics-say-about-roger-clem enss-steroid-use/

When taken in the context of the league and his overall best-fit career progression, it looks like the guy really was just in exceptional shape.