They have some strict policies. Other users can report an answer and have it automatically taken down without a staff review (as long as those users have good reputation) it can take as little as one user.

Sometimes they won’t even post your question, yet they still take away 5 points without notice.

Here is one question that did not post just because it contains a certain type of link:
Which actor is this?
http://answers.yahoo.com/question/index;_ylt=AkzbMWjDarA2kphGGEHlELfsy6IX;_ylv=3?qid=20100721181653AAOUGrT