Cyd,
First, life isn't fair. I'm not saying that people shouldn't strive to improve situations that might not be fair, but in the end true fairness likely won't be achieved.
Second, and more to the topic at hand - judges are not given a set criteria upon which to judge ballroom dancers. I've never seen any set criteria that says they must base 25% of a mark on footwork and 35% on frame and 15% on floorcraft, etc. So maybe that's a place to start. If judges have a set criteria it's somewhat more objective to see if the judges are actually basing marks on that.
Third, I've seen a particular judge who has a personal grudge against a certain couple. The judge NEVER marks them into a final, and the judge ALWAYS marks them last when the couple makes the final. Despite that judge's marks, the couple has still won events when that judge is on a panel. So, ONE judge's marks shouldn't make or break a result. That's one reason why there are several judges on a panel.
Fourth, I don't believe that EVERY judge who has a student in an event is automatically a corrupt judge. And, even if there is a corrupt judge it may not have to do with money/lessons - it may be something else that's affecting the marking of that judge. So tracking judges based on money might be a red herring.
I saw an event where a wife was on the judging panel when her husband was dancing in the event - and her marks put him in the bottom of the pack, which is where he wound up in the end. Should she have been on the panel? Of course not; but there it was. And seemingly, she didn't give him favorable treatment. Also, there were two other judges on the panel who I know had given coaching lessons to every single couple in the final. This was a small competition and if the organizer knocked three judges off of the panel, there weren't other judges on hand to fill in. If there were dancers who didn't like it, they didn't make a formal objection. Maybe next year they will quietly not attend that particular competition anymore.
So - in the grand scheme of things, maybe there's a judge who is marking a couple poorly or well for one reason, but then another judge marks a different couple poorly or well for other reasons. It probably all "comes out in the wash" in the long run.
There are unfair umpire calls in baseball and unfair referee calls in basketball - by supposedly impartial umpires and referees who don't coach the players. Why do they make unfair calls?
Are there unfair marks in ballroom dancing too? Sure. And if I see someone breaking a rule and if I can show chapter and verse of the criteria being broken, yeah, I'll raise an objection. But it's easy for a judge to justify a subjective mark when there are no set criteria.
So, after all of my rambling reply, in the overall scheme of things, there are other battles that I'm more willing to give my attention too.

The 'coaching'that Clary is discssuing is one of the things I have a real problem with.

The week before any large comp. is like a who's who of the ballroom judging world at my studio. I have so far refused to take part and I do win at comps over some of the competitors that I know are taking these lessons. Thus far I haven't seen it determining winners and a lot of the judging is where it should be. It still leaves a huge moral morass. It feels wrong and has the potential to go very wrong and I imagine it has influenced more than one outcome. Dual role relationships aren't best practice in any profession. Something does need to be done.

Words Words and more Words when the solution is so simple. NO JUDGE WILL JUDGE ANY PERSON OR COUPLE WHO THEY ARE TEACHING OR HAVING TAUGHT ON A TIME FRAME TO BE DECIDED ON. I think one year would be reasonable.
Heres one for you. A friend of mine received a phone call six weks before the event and was told you will not reach the final this year. And he didn't. He had stopped having lessons some few weeks before..
If you analize this. When he was having lessons and winning will he ever know if he was as good as the positions he was getting.

Do you realise, that if that rule was in effect, there would be no world class judges available for world class events ?...

Most top competing prof. and Amat. take from a variety of top class coaches who are pretty much all involved in championship events ( some judges may have 4/5 couples in any given event, and other judges the same in the SAME event )

Terence. What you say is true but that doesn't make it less corrupt does it. The system is all wrong. In Ice Skating are any of the judges teachers of the people they are judging. Tennis Umpires. Are any of the umpires coaches of the players on the court. Could you imagine that in the final of the USA titles the Umpire has a pupil on the court. I know. There are lines people on the court. But the final say belongs to the Umpire.
When you wrote you were thinking of a top competition. I say again at any level it should be stated clearly that no judge be allowed to judge their own pupils.
Have you ever struck the situation where where not one from a certain school entered because the principal wasn't invited to be one of the judges.
He Black Balled the competition.
I wonder if we will ever get to the stage and come right out into the open, where a comp is advertised as judges can judge their own pupils.
Terence It is usless to try to defend. Its rotten to the core.
You could probably quote a few instances were in the Adjudicators Room it came to, or near to, fisticuffs.
Shall i go on. A professional told me that this certain lady had a reputation for marking her own pupils. It has gone on for years and will continue. She will never judge a major competition. In my opinion she shouldn't be judging at all at any level. Its going to be a bit awkward answering this. You are forgiven if you dont. Its not possible to defend the undefendable. So why try.
By the bye. In a second hand shop I came across a Joe Loss LP. On the cover in a Ballroom pose is Ted Donaldson and Eve Barnett and Dennis Udell and Joyce Brampton. Both couples became British Champions.

Cyd,
I'm not sure that comparing tennis championships to dance championships in terms of the availability of "non-biased" judges. What is the purse for the winner at Wimbledon? What is the purse for the winner at Blackpool? There is a LOT more money involved in tennis that allows for umpires who do nothing but umpire, and coaches who do nothing but coach. In the ballroom world? Don't think so.
(Oh - and maybe someone like John McEnroe would have some comments on whether "unbiased" "unbought" umpires/judges called his lines fairly all the time.)
But at a small dance competition - disqualifying all the judges doesn't seem to be a great answer.

For your premise to work, it would take the collusion of NINE judges to affect a result ( smaller comps would work under the same premise )..

yes, I do realise that in "local " in house events, things are not always what they seem to be..

Hi,
I believe that should be, Eric and Edna,

Scenario - SMALL competition: 7 judges total available at competition. Three couples on the floor have taken coaching lessons with ALL 7 judges among them. So, under your proposed rule ALL 7 judges are to be recused. Who judges?
I don't find that so simple to resolve. But I'm interested in hearing ideas.

Clary.If the rule was made that no judge will be allowed to judge their own pupils. Then they would have to make up their mind wether they want to be a teacher or a judge.
I dont think some of you guys know what goes on. One of the top coaches when it was made known he would be judging. Within a few hours he hadn't got one available hour left on his calender. When he said that he would be available, but only after the next competition . The responses was the same every time. I'll get back to you later..
The best one I ever heard was a judge who marked a couple who wasn't there. They hadn't turned up even though they were numbered in the program. Unlike Blackpool where the judges have a card with each competitor numbered in that heat. Here we do not. The judges have a blank card. So this guy popped the number they would have had down on his card Just for your information out of say nine judges to get through to the next round three ticks would probably be enough.