About ebooks and the hideous PDF

Hey guys, I have a question/request for help.
I got a Kindle, and I use Calibre as sort of “itunes” for my Kindle because it can convert from almost everything to Kindle format.
My question is, what’s the best way to transform a PDF? I’m asking because 8/10 uploads in the ebooks sections is in PDF FORMAT! And it’s a terrible format to convert to Kindle! Calibre converts them, but either the font is small, graphics are bad or the pdf looks corrupted.
TY
Answer #1
You could try K2pdfopt.
http://www.willus.com/k2pdfopt/