If you're using Google Adwords to drive traffic to your website then you need to read the latest post on Google's blog. They're really cracking down on salesy websites. This is a good thing because there are so many crappy websites out there selling garbage.
http://adwords.blogspot.com/2007/09/websites-that-may-merit-low-landing.html
Make sure you comply with Google's landing page guidelines at https://adwords.google.com/support/bin/answer.py?answer=46675&hl=en or they will increase your minimum bid prices through the roof.
Here's a great guide written by Jeremy Palmer from www.quityourdayjob.com. I highly recommend getting on Jeremy's email list because he's on top of the latest Google trends. http://www.quityourdayjob.com/qualityscore2.pdf
