a brand new capsule, or one in good state, will not cut out, unless you really drench the capsule in humidity. (With any electrical circuit, there are limits to how much humidity it can handle.) With cleaned capsules, it depends on the state and type of soiling, on the expertise, and then on a bit of luck, how good you can get. Some capsules are so ruined, we do not even attempt to clean them; others can be returned to almost-state-of-first-shipment. Multiple goes at cleaning are not recommended, too much can harm the diaphragm and gold layer. If the state of the capsule is such that there is no audible noise effect with standard use, with a pop shield and at typical singing distance, I would call the cleaning attempt "successful".
BTW, I myself never clean capsules; I leave that to the colleagues who do that on a daily basis.
Best regards, Martin Schneider / Neumann Mic. Development