No, not to the best of my knowledge. Something has to be really bad to be culled.
It's something to do with the software, I think.
I have noticed recently that if I go straight to a forum and miss out the top 50 list, I see a thread or two sitting there in the individual forum which I really don't remember seeing on the Top 50. This happens occasionally with things I post too - they appear on Home and in the individual Forum chosen but don't appear on the Top 50.
It's that kind of problem and what the answer is, I don't really know.