*WARNING* MAY OFFEND PEOPLE
Palpatine, especially in the prequels prequels, is exactly what you would think of when your idea is "hmmm everyone except the characters know the dude's evil" vibe.
Honestly, I remember being a small kid when my dad made me watch the prequels and when would always ask "hmm, I wonder who Darth Sidious could be?" And I used to always laugh and say "it's obviously Chancellor Palpatine, Dad!"
Honestly, thinking about prequel-era Palpatine makes me long for the days Disney hadn't created the sequels yet.
I'd give Darth Sidious a 9.5.