T.A.P. Test: Timeliness, Authority and Purpose
Timeliness or currency
Is the resource dated?
Example: http://geosim.cs.vt.edu/
Authority
Who wrote it? What are their credentials
What is the quality of the writing?
Example: http://www.nature.com/scitable/blog/saltwater-science/saving_the_swimming_dead
Purpose or Objectivity
Is there an ulterior motive?
Is it educational in nature?
Is there a lot of advertising?
Example: http://www.monsanto.com/newsviews/pages/india-farmer-suicides.aspx
Other criteria to consider: