Are scent dogs unreliable, is it junk forensics?

Two federal lawsuits are casting a harsh spotlight on an investigative tool long beloved by American law enforcement: a bloodhound's nose.
Lawsuits filed in Victoria, Texas, allege that Fort Bend County Sheriff's Deputy Keith Pikett and his team of hounds — James Bond, Quincy and Clue — failed controversial sniff tests known as "scent lineups."
Much like in traditional lineups, the dogs link human scents left at crime scenes to samples from suspects.
In each case, the suits allege, Pikett's dogs called attention to the wrong person. Both former suspects have been cleared.
Defense lawyers say the technique smacks of forensic voodoo and casts further suspicion on the broader use of scent dog evidence.
"It's a fraud on so many levels," says Jeffrey Weiner, former president of the National Association of Criminal Defense Lawyers.
Since 2004, two men in Florida and one in California have been freed after DNA evidence exonerated them. They had been convicted, in part, on the use of scent evidence, according to the Innocence Project, which uses DNA to exonerate the wrongly convicted. Pikett's dogs weren't involved in those cases.

Link: http://www.usatoday.com/news/nation/2009-06-29-scent-lineups_N.htm?csp=34