The scientific method is the best thing we have for testing the veracity of theories of any sort. If a theory cannot be "proved" by the scientific method then whatever it is can only be on very dodgy ground.
An example would be homeopathy for which there is no scientific evidence that it is any more effective than placebo. Defenders of homeopathy tend to point scientists to the ample amounts of anecdotal evidence and then argue that homeopathy doesn't work well under scientific conditions. However, anecdotal evidence is notoriously unreliable and the fact that it doesn't work well under scientific conditions suggests that it doesn't work.