The operative word is 'net', Mark. Who is to say what classes as deductable expenditure before net profit is declared out of the gross?
I never go anywhere near stuff like that. Some companies trade on the names of charities yet give them only pennies for the priveledge. The charities keep quiet because it's income they wouldn't have had.
30 years ago, every Christmas we used to get a pack sent to us unsolicited by a company claiming to support Foot and Mouth painters. It was an honour thing, and if we kept the cards it was hoped we pay for them. Inside were Christmas cards painted by armless artists holding brushes in their mouths, or their toes. The packs cost the equivalent of £6.00, in small print it said the amount paid to the artists was 12p! Hence, I buy my Christmas cards direct from charities these days.
I also go for the best deal I can get, and send a cheque for a tenner to IFAW, or something similar once in a while....