Well, of course individual judges have biases and sometimes favorite skaters.
But that kind of favoritism will vary with the individual judges and they'll cancel each other out.
When all the judges score a certain skater higher than jump content or artistic appeal to fans would suggest, it's more likely in response to something about the actual skating that may not translate well on video than to all the judges getting together and conspiring to overmark that skater.
It works on both sides of the coin - the Technical Elements as well as the Component Scores.
COP allows judges to have possibly a big influence by applying very positive GOEs for a skater's completed elements (effect multiplied by up to 12-13 in the long program) just as much as applying inflated component marks...
As has been said time and again on this board, Kostner and Lepistö have some of the best basics of any skaters of the CoP era. Those who were booing may have been watching their jumping instead of their skating. The judges look at both.
Also, with respect to 2008, much of the booing was due to fans' perception that the fourth-place finisher, Yukari Nagano, had landed a triple axel in the Free Skate. The jump was marked as underrotated.
But with only 9 judges it's mathematically possible for an imbalance in the bias of the judging panel that isn't cancelled out by others on the same panel to make a difference that is very noticeable to many fans. Someone mentioned Lepisto's bronze at 2010 Worlds. She edged out Miki Ando by 0.8 points for that bronze.
It doesn't take much non-cancelled out bias for that to have happened (I'm not saying it did happen).
The main points are still:
1. Judges are only human not machines.
2. Their natural, unavoidable bias cancel each other out or don't matter in the overwhelming number of competitions
3. Some fans have a bias toward remembering only the few times when they think (but have no proof) that judge bias affected the standing/medals/results.
4. The correct judging of skaters based on the quality of their performances is the norm to such a degree that obsessing about the few exceptions is pointless.
5. Natural human bias is NOT the same thing as konspiracy.
Also, blades matter, but jumps should matter too. I mean, this particular case was a double jump fest from Lepisto. I get she might have nice edges, but for crying out loud, you have to actually be able to land some triples to be a worthy world medalist. At least in my book.
Did I mention that the sizes and length of blades also go into the scores?
But fans at that time were even more inclined to attribute results they disagreed with to politics rather than to a difference in priorities.
Judge's favorites are the skaters whose under-rotations and wrong edges aren't called as regularly as other skaters, those who may fall but somehow haven't, and whose pcs is always high regardless of the quality of the actual performance.