The tricks in charity are legion.  The most obvious and common scam is donating goods in kind (art and other collectibles especially).  A receipt far in excess of the value of the goods is issued and both parties walk away happy.  

Registered charities needn't pay tax on the proceeds of the sale, so even if they issue a 10K receipt for a piece of art that only sells for 500, they are still 500 ahead.  And the wealthy donor has earned him or herself a 3300 dollar deduction.

Individuals and charities have both been caught doing this, but if they  don't get too greedy about it things generally pass under CRA's radar .  As the old saying goes, pigs get fat but hogs get slaughtered.