From RemyWiki

[edit] Sorting

Songs are sorted along the following algorithm:

• Non-autoscratch scores will always sort above auto-scratch scores.
• Scores are sorted primarily by ex score.
• Scores are then sorted by individual note counts (just great, great, good, bad, miss). Alternate entry mode scores will always sort lower than ones with full note counts.
• Finally, if there is a tie all the way down the line, scores are sorted by date entered.

If you ever see a score listed at the bottom of the pile when it is higher than a number of other scores, it's because of auto-scratch settings.