because bodybuilding is basically a pageant, where the competitors themselves are the product.....as compared to another sport where the product might be how they throw a ball or ice skate.
and since they are the product, it is IMPOSSIBLE for anyone to completely separate themselves from their feelings about that person when judging their physique......whether it is readily apparent, or more understated.....its always there
i try very hard to be completely objective, but even catch myself doing it sometime.........and i have NO vested interest in these guys and dont know them personally........now think of how impossible it is for these IFBB/NPC judges who are friends with many of these bodybuilders, do business with them, have them posing at their shows, such and such bodybuilder trains at this judge's gym......
the point is, personal feelings DO play a role