You know, I have never read an explanation of the "science" behind the "spit" test. Frankly, I have little confidence in the "spit" test.
Part of the problem with candida is that there appears to be no test that is universally accepted as being definitive proof for the condition. One blood test sounds interesting. A blood sample is taken form the patient. The patient is given a measured amount of glucose to drink. After a specific period a second blood sample is taken from the patient. Both blood samples are tested for ethanol. If the patient has a candida overgrowth, the second blood sample should have a higher ethanol content. The candida converts the glucose into ethanol which goes right into the bloodstream. It may be possible to correlate the amount of ethanol in the blood which the severity of the candida overgrowth. An ethanol blood test is relatively cheap and easy.