They are, in millions of lab notebooks around the world that will never see the light of day, and for good reason. There are so many more experiments that end with the unqualified final note "samples contaminated" than successful ones that if biologists spent time tracking down the source or even the type of the contamination, we probably still wouldn't have modern medicine.
Is there any kind of survey of all failed experiments and the causes? What are the numbers? What percentage of experiments fails? How can we be sure the successful trials weren't random if the failures aren't reported in any way?
You seem to be conflating all possible modes of failure under the simplistic designation "failed experiment" and setting up impossible standards for record keeping. The clinical trial equivalent of sample contamination is a patient getting hit by a bus minutes after they receive the first treatment of a trial. Sure if its a psychoactive drug you would investigate if it contributed and you can include this tiny little blip of data in the thousands of other pages you give to the FDA but what's the point? The trial was ruined by an unpredictable act of nature and your resources can be much better spent focusing on the other patients than investigating if the driver was intoxicated or if the hospital needs more stop signs, which are entirely irrelevant to whether or not your drug works.
I am by no means advocating that well thought out and executed experiments that fail to provide evidence for the experimenter's hypothesis should be locked in a dusty file cabinet forever closed to study, but those are few compared to the total number of experiments that ended due to clumsiness, sleep deprivation, or too many undergrads in the lab. Science is all just human error, through and through.
