No doubt we could devote an entire conference to this question. But to those of us in advertising, truth is what is understood by the consumer, not what is actually said or shown. Because it's bad business to mislead consumers, it doesn't happen very often. Indeed in terms of national advertising in the U.S. and Canada, it can't happen. National advertising is the most regulated form of communication I know.
Taste is very personal and certainly varies from culture to culture.
The nudity so freely allowed in European advertising for bath products and fragrances would be seen as highly offensive in other cultures. The graveyards of marketing are filled with products that were heavily advertised but nobody wanted. New Coke, Polavision, Corfam, to name a few. And all the advertising in the world couldn't make people want the Edsel. Again, the consumer is the ultimate judge as to whether products succeed or fail.