Why do some charities offer a free physical gift when you donate money of any amount, but then they…

have a check box at the bottom saying “Check to let us keep the gift”?

What would you do in a situation like this? Is it appropriate to consider the free gift – USB drive, tote bag, etc. — as the motivator to write a check rather than valuing the vision of said charity? Would the charity’s message even matter if there were no “you’re welcome” gifts offered? Would this fit in the “deal or no deal” hemisphere?

Speaking of charities, how well do you handle with the pile of letters and emails asking for help on good causes?