ya man... like how 'ice cream' is actually sugar dough with dry ice. most of the stuff inside advertisements aren't edible at all... 'artificialized' to make the prolonged shoots possible.
There was probably many horror stories tho. My galfren was involved in the advertising shoot for Nutrisoy (the one with the girl in the gym).. apparently, they had to take so many reshoots that by the final take, the girl was drinking beancurd, coz the soy milk in the packets had soured and curdled. After the 'cut', she rushed off to vomit...