This is an interesting question. I submitted this link yesterday, and it did not make it to the HN homepage. Still, I was almost certain that it could start an interesting HN discussion to read. Today I chose to repost it with a clear ?repost rather than a less visible trick, and it was still upvoted (better timing I suppose): the fact that it is a repost did not seem to bother the upvoters.
I have no solution to propose, but the timing seems to be the most important factor for HN submissions, as we already know [1][2][3], and I think these small hacks are acceptable to work around the problem: reposts are not a big source of pollution, and users can report abusive behaviors with the flag button.
[1] http://hnpickup.appspot.com/
[3] http://jacquesmattheij.com/How+to+make+the+Hacker+News+homep...