I've been contacted by a charity who is not happy that they were listed as a donation option for ClearCoin charity escrows.
I made the mistake of assuming that charities would appreciate the extra bitcoins; it never occurred to me that ClearCoin customers might contact a charity and ask THEM for their (supposedly-donated) coins back. Charities can't be expected to resolve ClearCoin disputes.
To fix the problem, I have disabled all charities for new escrow accounts except one: the Bitcoin Faucet. I will be writing to any charities that received ClearCoin donations from already-created escrow transactions to make them aware of the situation and will ask them to forward any ClearCoin-related issues to me.