Know-How Exchange : Advertising/PR

My Question is Related to celebrity endorsement . As far as the performance of a celebrity endorsed product is concerned. it's positively correlated to the performance of the celebrity in whatever field the celebrity is connected with no matter if the product he endorses is relevant to his profession or not. My question is that as we all know the investments in celebrities have its own risks tied to it. The celebrity may lose in a game, may be found connected with socially unaccepted behavior, becoming replaced with a new superstar etc. so what are the ways by which the maximum return from the celebrity investments can be made. I want to know those ways by which those risks can be mitigated, reduced, eliminated etc. is it possible to measure the risk associated with each celebrity depending upon the nature of the celebrity environment. Because the sport stars gradually rises to sublime and gradually lost to fame, whereas the movie stars rise in a day and fall in a day. Similarly is there a life cycle for the celebrity to pass from infant stage to adult stage? If it is there how to predict the risk tied with the celebrity who is found in declining stage suddenly in one fine morning. For example a political leader who is famous for various reforms he brought to the nation will be despised if he was found guilty in pocketing the nations money. His charisma and mass will fade in a night.