The Halo effect is a cognitive bias where an observer’s overall impression of a person (often based on one positive trait or aspect, such as fame) influences their ratings or judgments of that person’s other traits or abilities.
In this case, the contestants’ fame from T.V. appearances led the raters to give them higher scores, regardless of their actual performance in the pageant. This happens because the positive impression of the contestant's fame spills over and biases the raters' judgment, causing them to view the contestants more favorably in other areas as well.