When would someone need a candida cleanse? After a round of antibiotics. After a period of high sugar/alcohol consumption. When experiencing recurrent yeast or fungal infections. During a detox. When addressing chronic gut issues. If diagnosed with candidiasis or yeast overgrowth by a doctor. 
Since 70-80% of the immune system is in the gut, excess Candida can strain immune responses. A cleanse may help reduce inflammation and give the immune system space to recover and recalibrate. 
Symptoms of Candida Overgrowth: 
-bloating, gas, constipation or diarrhea
-sugar or carb cravings
-brain fog or poor concentration 
-chronic fatigue
-recurrent Yeast infections 
-skin issues 
-white coating on tongue
-vaginal itching or discharge