Here is a very good video about faking ghost & orb pictures, and how to tell if someone posted one.
Jason Sullivan of Midwest Haunts goes through the 4 most common steps used in faking a Ghost picture. Call them busted, this is a great video if you're interested in knowing the truth about paranormal photos.
http://vids.myspace.com/index.cfm?fuseaction=vids.individual&videoid=16581233