The New York Time publishes some the best essays from there competition on their website every year. You can read those here; http://www.nytimes.com/interactive/2015/05/20/your-money/college-essays-on-money.html?_r=0
Also check out the Essays that Worked book, which consists of essays that got people into Ivy League or other top tier schools. You can probably find it free as a PDF somewhere online.
Common app has this info on their blog here; http://blog.commonapp.org/2015/03/31/2015-2016-essay-prompts/
The changes you see reflect the feedback and consensus of nearly 6000 individuals who responded to our recent survey. Among the survey highlights:
197 individual Member responses representing 110 Member institutions
5667 constituent responses (64% school counselors; 14% students; 11% independent educational consultants; 4% parents; 2% community based organizations; remainder = other)
82% of Members and 90% of constituents agree or strongly agree that the current prompts generate effective essays on the whole
62% of Members and 48% of constituents believe the “story/background” prompt is the most effective
76% of Members and 44% of constituents would like to see the “place where you’re content” prompt replaced
35% of Members and 30% of constituents feel that analytical ability and intellectual curiosity (as a combined percentage) are most the difficult attributes to convey through the current prompts
85% of Members and 82% of constituents feel the prompts should be left open to broad interpretation
3% of Member respondents suggested Topic of Your Choice as a new prompt
6% of constituent respondents suggested Topic of Your Choice as a new prompt, with the breakdown as follows: independent educational consultants (47%), community-based organizations (7%), school counselors (5%), parents (2%), other (2%), students (<1%)
As for bad essays I have no idea.