I do believe there is a subconscious bias present in almost all competitions, though I am not quite as certain if there is a political factor. Nonetheless, for either case it is difficult to determine the degree of influence it has on a particular competition. I imagine familiarity with each band is directly related to this degree of influence. With only 7-12 minutes to judge a great deal in regard to the quality of a band, it is likely inevitable that the subconscious will play some sort of role in determining a score relative to other bands.
In this case, I define political influence as deliberate influencing of a score. As for bias, I define it as subconscious influence of a score. I would expect that a great amount of the time, people put too much blame on the judges, confusing political influence with subconscious bias.
In some instances, I would imagine that subconscious bias is present enough to possibly affect the placement of a band. However, the scores will almost always reflect the general order of quality of bands on that particular day.
Its up for grabs as to how many judges deliberately place bands in relation to other bands. But, I do not think they can get away with much, in light of the fact that it would look astonishingly odd if one judge's scores were completely contrary to the other scores.
Then again, judges have different opinions on what is good and what is bad. I think that may also be confused with a political factor as well.
All in all, I do think that bands generally get the score they deserve, give or take a place or two. But people need to stop worrying so much about placement and more about the performance itself. You could debate forever about what place a band should have gotten. Politics and biases aren't going away any time soon. If work is put forth toward the performance, and a complete mastery of integration of musical and visual elements is demonstrated, you will get what you deserve. If work is put forth toward the score, a lack of understanding of the performance is present, and it will reflect a score that is able to be tampered with.
Then again, maybe I think too high of judges, and they will really go that low to "keep bands in their place" or whatever. One can only hope that is not the case. I do believe that judges rarely "hate" bands, however.
Basically, I think if your score is subject to such influences to begin with, politics/biases are the least of your worries.
Shrug. Just put on a good show.