Can humour in advertising ever detract from the brand message?
The humour has to be appropriate for the context – if it isn’t, or it is too offensive, the brand is tarnished/discredited.
Can you explain why humour used in public health campaigns or charity ads can be more effective than attempting to leverage other emotions?
It comes back to how manipulated viewers/readers feel. If done well, manipulating all emotions can be effective, but humour is safer because we would rather laugh than cry or recoil in horror. And humour is a better persuasive tool than sadness – there’s a lot of evidence showing that we like people who make us laugh and we are more willing to help. So, an advert that makes us laugh might be more likely to make us help.
A good mood makes us more receptive to co-operation and offering resources. People in a good mood tend to gamble more, for example.