Even if there was no 'unaccounted for' funds and fraud, there is a lot of charities who will flat out tell you that many times only 20% of the money collected goes to the people it was collected for. I've seen some as low as 2%. BTW, its not always easy to get this number but if you are persistant enough you can get it. It may take some time and 4 or 5 transfers but by law they have to give it to you. Also, as long as they don't lie about the percentage numbers, its all legal no matter how low it is.
Never give to any charity without getting this number first. If you want to have some fun the next time you are in the check out line and the clerk asks you for a buck for tragity X, just say, "That sounds great, but first I need to know what percentage of this money will go to the victims of tragety X." Of course they will not know and you say, "Well maybe next time if you can find out that little bit of info for me." Hopefully, this will get the at least the clerk and maybe someone else within ear shot to think about this problem.
In the end charities are just a mechanism for the rich to get richer using the sob stories of legitamate victims.