for charity I think it should be clean, because charity is not joking. it's sort of a religious thing. so I think bitcoin is not good for charity, because it is unstable and it feels like gambling.
I do not think that there is anything wrong if a person is giving donation in crytpo currency, because it is very much easy that convert your bitcoin or any other crypto currency in to bitcoin. So i am sure that some charities must accept crytpo currency as donation.