What is candida spit test? reliable?

Nope.: The candida spit test is pseudoscience. It is a crude indicator of how thick your spit is, and that's about it. There is no reason to believe that spit thickness correlates in any way with the presence of candida, nor is there any scientific evidence that it does. It yields both false positives and false negatives, and in one study, its accuracy was no better than random guessing.