Just personal opinion, but I wouldn't risk ceramic in close proximity to my lungs at all. And if there is any burning on the wicking material that coil is done for anyway, like the picture Punk In Drublic showed. If you can detect even the slightest burned taste, there is no coming back from that and the coil will never taste the same and as was stated above can degrade the ceramic from 2 perspectives. The material will weaken and start shedding material... which winds up in your lungs. It also will degrade the capillary action and will not be able to control the juice flow the way it is intended to. So even if you clean it as best you can, it will not be the same vape and is potentially harmful.
If you clean it on a regular basis before there are any signs the coil is not performing properly, just as a routine maintenance you might be OK doing that. But generally I wouldn't clean a coil that was still working properly. You may be more regimented than my slovenly ways (or OCD...lol), but if you hold off until the coil is no longer working well I would say it's a lost cause. But just personal opinion from my experience.