Parapunter, be very very glad it was flour/talc and not red lipstick!!!!
(Yes I've had the misfortune of being on the receiving end of a wall full of red lippie, courtesy of my 2 year old cousin....)
Nanocas, most aircraft actually will have some sort of change facility in the restroom, on the aircraft that don't the crew would usually only be too happy to give you a folded blanket to lay across the closed seat in the toilet to use as a mat, that is if they dont have one of the portable table/mat contraptions (lots of aircraft with no table have a seat which closes flat to the 'platform' of the lav for this purpose...) I do agree if you're on a small plane (like 10 seats or something) then it may not be avoidable... but if you're not sure, ask, we're here to help
I don't have anything against kids themselves, as I said we've had many lovely children on flights, a few weeks ago we had one delightful little bloke who wanted to help us pick up all the rubbish and also hand out the arrival cards (of course we okayed it with mum & dad for him to collect rubbish, lol) He had a great time, future cabin crew in the making!!!!