When displaying Questions sorted by votes using the following URL (with 15 questions per page enabled!)
https://skeptics.stackexchange.com/questions?page=67&sort=votes&pagesize=15
afte the lowest voted questions the list continues with high-voted questions:
The questions don't seem to be entirely sorted by votes, the order looks somewhat broken.
This also happens on Drupal Answers on the following page (screenshot)
https://drupal.stackexchange.com/questions?page=67&sort=votes&pagesize=15
and on Physics
https://physics.stackexchange.com/questions?page=67&sort=votes&pagesize=15
and on Gaming
https://gaming.stackexchange.com/questions?page=67&sort=votes&pagesize=15
It is not always reproducible, occasionally the right order appears. I saw this on every SE site I tried it on, including Stackoverflow itself.
I've looked a bit further and found that exactly the first 1000 questions are sorted correctly, afterwards it goes wrong. The pattern repeats every 1000 questions, so after 2000, 3000, ... questions there is another break in the sorting.
I've observed this now for a few weeks, so this is not a temporary caching problem.