What are the spiciest billionaire romance books?

Of the 12 billionaire romance books smutrecs.com has rated, the spiciest are Fifty Shades of Grey (5/5), Bared to You (about 4–5/5) and Reflected in You (about 4–5/5). 8 of the 12 are rated spice 4 or 5, on a scale from 0 to 5.

1. 
   Fifty Shades of Grey by E. L. James spice 5/5
2. 
   Bared to You by Sylvia Day spice about 4–5/5
3. 
   Reflected in You by Sylvia Day spice about 4–5/5
4. 
   Liars Like Us by J. T. Geissinger spice 4/5
5. 
   Twisted Love by Ana Huang spice 4/5
6. 
   Black Ties and White Lies by Kat Singleton spice about 4/5
7. 
   My Dark Romeo by Parker S. Huntington spice about 4/5
8. 
   Wild Love by Elsie Silver spice about 4/5
9. 
   Forever After All by Catharina Maura spice about 3–4/5
10. 
    Misconduct by Penelope Douglas spice about 3–4/5
11. 
    King of Greed by Ana Huang spice 3/5
12. 
    The Right Swipe by Alisha Rai spice about 2–3/5

Each book page lists the sources behind its ratings. Ratings marked "about" are estimates. How we rate