Is PCR considered a valid test?

Is PCR considered a valid test, because I was looking on the Quackwatch website and they list PCR.  I thought PCR was mainstream.  They probably jumped on it when it first came out and never took it off!

KO

The "doctor" who runs quackwatch has been sued. He isn't a practicing doctor (and his field of "expertise" is not physical medicine but rather psychiatry/psychology), apparently has made it a personal mission to speak out against any treatment other than pharmaceuticals, even bad-talks FDA approved treatments such as accupuncture for pain.
I wouldn't trust everything you read on quackwatch...look for independent verification. He likely has twisted the facts to support his viewpoint.

While it is true PCR is not a perfect test, technology has advanced since the first PCR tests were developed. Keep in mind, however, that a PCR test can only detect DNA that the test is specifically designed to look for -- this can still lead to false negatives. There are usually no false positives with PCR, though, so a positive result is pretty solid.