Celebrity endorsement advertising has been recognized as "a ubiquitious feature of modern marketing". This study raises two questions. Both questions relate to the consistency of celebrity endorsement source credibilty in multi-brand advertisments featuring the same celebrity. The study draws important results which suggest that negative publicity is more powerful compared to persuasive advertisements featuring popular celebrities. The study also suggests that celebrities are not a substitute for corporate credibility or sound brand value proposition. For the analysis, popular brands such as Coke and Titan - both of which are endorsed by Aamir Khan- have been studied. The results reveal significant differences in the celebrity's credibility while endorsing both the brands. There is also a difference in the believebility of the TV advertisements of the brands while featuring the same celebrity