good/bad charity

That's a really hard choice. I guess it would depend on the long term effects of this corruption on the people that are being helped by it, on the other hand knowing of corruption and not informing authorities of it sounds a bit criminal too. Depends on how far that corruption goes up the chain of command too, if it's at the highest level, then there isn't much you can do, however if it hasn't purhaps I'd go to the highest level and expose it, so that it could be sorted out internally.

Since you say you have found out, I'm assuming this means that you have actual proof, not just either relaying on someone elses opinion or found information on the net? That's a really hard one, because on one hand there is all the good being done while on the other hand there is something wrong which goes against the reason for the charity in the first place. It would depend on what the corruption is - using donations for admin costs for example or individuals taking donations for their own personal use. I suppose the choices come down to: 1) Try to do something about it, but if it is widespread there probably isn't much you can do 2) Quit 3) Continue working there and keep doing the best you can, at least there will be some honest people involved. Sorry I can't be of any real help.