The Baroque Cycle/YMMV

• Complete Monster - The Earl of Upnor has no redeeming qualities whatsoever. The other bad guys might be Affably Evil, might be Magnificent Bastards, might have sympathetic motives, or might have standards. But not Upnor. Upnor is a nasty, vile, evil sack of scum who exists solely to make the reader hate him.
• Crazy Awesome - Jack and Jeronimo walk a fine line between sanity and insanity and are really awesome because of it.
• Epileptic Trees - Tons of them involving the Solomonic Gold and the true nature of Enoch the Red.
• Nightmare Fuel - Daniel's kidney stone operation and the story of how Jack became "Half-Cocked". The descriptions of the effects of smallpox and the attention paid to 17th/18th-century sanitation (or the lack thereof) probably count as well.
  • In-story, Hooke and Wilkins' experiments at Epsom provide Daniel with this.