Are there any circumstances in which information from advertisements is likely to be more influential than word of mouth?

This is the case in all circumstances. An Absolutely fantastic example would be the advertising method employed byMacDonald's the quality of the product is atrocious yet people eat the stuff in preference to better quality product. if you want your kids to eat broccoli or Brussels sprouts all you have to do is put it in a bag or package with Ronald McDonald on it. Advertising is most definitely the most influential. Advertising is so powerful that young people think an Apple pie is a rolled up pastry tube with Apple in it that has been deep fried in cheap oil.