The only sure way to pass a saliva test for meth (methamphetamine) is not to take it for at least four days. The test can detect use anywhere from 1-4 days before.
However, there are several products on the market claiming to help either to pass the test with meth still in your system, or to speed along the detox process.
Whether these products work or not seems to depend on the person taking them, but the product 'Rapid Clear Spit Clean' comes with a 500% money back guarantee, which suggests a high success rate!
The website claims the product works quickly and lasts for half an hour. It's available to purchase here:
This site and others claim that the saliva test is easier to pass than both urine and hair tests.
If you don't want to fork out for products claiming to help you pass, there are several home remedies that have worked for others taking the test. It's important to note that home remedies can't guarantee results, as the tests often change and develop in order to stop discovered tricks from working, but have worked well for some people.
Eating an orange whole, including the skin, has helped some people pass without detoxing, which they attribute to the citric acid. The science behind this is dubious, but several people suggest it.
Drug Talk TV have put out some tips especially aimed at passing a drugs test for work, hosted by 'the people's drug testing consultant', which you can watch here:
Things to watch out for are products described as 'masking agents' as these can be dangerous for your health. Also any 'home remedy' suggestions that involve ingesting or rinsing with harmful chemicals.
Natural methods or products, such as those suggested above, have a higher success rate than methods which may cause serious injury to yourself.