Five items assess a person's general attitude toward the individual featured in an advertisement—whether a celebrity, model, or average consumer—on believability, attractiveness, competence, persuasiveness, and likeability.
Martin, B. A. S., Lee, C. K. C., & Yang, F. (2004). The influence of ad model ethnicity and self-referencing on attitudes. Journal of Advertising, 33(4), 27–37.
Free access to 2023+ psychometric scales at PsychScales