When salespeople, marketers, and job interviewers add on extras, they undercut their pitch.
During an interview, your potential new boss asks you to briefly describe your qualifications. At this moment, you have a single objective: be impressive. So you begin to rattle off your list of accomplishments: your degrees from Harvard and Yale, your prestigious internships, your intimate knowledge of essential software and statistical analysis. "Oh," you add. "And I took two semesters of Spanish in college." Not technically an impressive accomplishment, but since the company does a lot of business in Latin America, you figure some Spanish is better than none at all.
Or is it?