Is there a massive amount of code errors? Are on-site links text, flash or images (text is best)? Does the page take forever to load - bad for SEO? Does it look like the site content emphasizes keywords that they should be found by? Are these keywords at the beginning of the title, keywords, description, main content, image alt tags? Is there a visitor sitemap? Is there a sitemap.xml? Is there a robots.txt? I am sure others can come up with more to add to the list...