Your answer might be here: https://www.google.com/adsense/policies
However, it seems like this would be the reasons for rejecting a site from the beginning:
In addition to the standards above, AdSense participants are required to adhere to the webmaster guidelines posted at http://www.google.com/webmasters/guidelines.html.
Some relevant items from the guidelines are included below for your reference:
Do not load pages with irrelevant or excessive key words.
Do not employ cloaking or sneaky redirects.
Do not create multiple pages, subdomains, or domains with substantially duplicate content.
Avoid hidden text or hidden links.
Keep the links on a given page to a reasonable number (fewer than 100).
Do not participate in link schemes designed to increase your site's ranking or PageRank. In particular, avoid links to web spammers or "bad neighborhoods" on the web as your website may be affected adversely by those links.