BitComet reports wrong stats to other peers as well as the tracker, and does not share well.
I'm not so good as ett, but only problem with seeding which I have with version 0.70 is while I'm downloading something else - usually it's not willing to use remaining upload capacity for seed. Ok, other clients could be really better.
But I really doubt about wrong reporting, it was true but it should be already fixed for some time. I'm not bittorent expert but what is reported to user seems fine and if it really uses some dirty tricks to priorize itself, which I doubt because it's serious client and not last hacker's attempt, at least noone is really harmed at the end if user behaves as he should.
Anyway, I hope you ban also BitComet seeders when you are downloading something, Psychiclord. Just to keep our sharing relations balanced, because I seed for everyone