Blog-style sites (ie: data-life engine, wordpress etc..) will rarely see anything above 3 stars.
There are certain circumstances that will result in a site being rated 5 or 4 stars where they may have an ad. Usually these sites offer something significant to the community they serve. They are mature, offer clean content, maintain their site, offer something unique, etc. Sometimes, large sites who own their own dedicated server need to pay for costs through advertising. Generally, 95% of the warez/porn sites out there use shared hosting, and do not need ads to pay for their site -- they are looking to make a profit.
Blog-style sites will rarely see anything above 3 stars. Many will see 2 stars or less when being rated. Whilst blog-style sites are easy to maintain, they are very impersonal. They do not contain a community feel, and many of them are of poor quality, ad-ridden, and leech content using leech scripts.