You must not have read either the ToS or the advertising policies here at WordPress.com. If you intend to have a blog designed to promote adsense, advertising, affiliate links, get rich quick programs, banner ads, consists solely or mostly of duplicate or automatically generated material, or is part of a search engine marketing campaign, WordPress.com is not the place for you.
No blogger initiated advertising, retailing or reselling the work or products created or services provided by anyone other than yourself is allowed on free hosted WordPpress.COM blogs. E-commerce transactions via shopping carts and the like cannot be conducted on free blogs from and being free hosted by WordPress.COM
I suggest that if these realities are deal breakers for you then you can hire a web host and set up your own self hosted WordPress.org install from http://wordpress.org/