Well, if you know that the bitcoin comes from illegal activity perhaps it will change your mind and not accepting it but without knowing that you have received funds as a donation from the charity so does not matter now as long as you don't know. There is no clean or dirty on bitcoin, just like fiat, --or even much worst because you have received personally in physical the money which is you don't know where it is come from. The same on the bitcoin price, we must be considering it first, in every transaction on bitcoin as long as it can't be traced you are always be safe.