Endings
All three endings
Three endings, one bad name
GameSpot's ending article describes three outcomes. False and bad are the same ending, not two. This page calls it the false ending. There is not a fourth ending hiding under another adjective.
The false ending triggers if you enter Dracula's Chamber in the loop that starts when you chase Isaac and Dracula after the Clock Tower. Walking in is enough. The article says Rose receives a costume for seeing it, so it is worth doing on purpose once.
Normal, then good
The normal ending continues after the false one. You take The Shadow in Notre-Dame, which means the painting is open: The Builder, The Artist, and The Occultist. Beat Isaac at the top of the Clock Tower and Dracula. After the second phase, do nothing. That passivity is the normal ending as the article describes it.
The good ending needs the Four Virtues first. Courage is Joan's Notre-Dame rematch. The Whisperer is the Miser path: three eyes, Mammon, then the coins to the ferryman. The Judge is the Judge's test. The Sage is the four seals, the Temptress, and the Tomb of the Noble Queen. Then enter the central stained glass, beat the Doppelganger, take The Self, and finish that card's Works of Mercy. The Self's tasks include a one-spell kill of four enemies, five times, 85 percent map exploration, and ten full heals from the spell.
What I ran into
I spoiled myself on purpose so the conditions would be conditions and not vibes. The 'do nothing' line on the normal ending is the one I did not believe until I read it again. It stays, because it is the difference between two clears.
Questions
How many endings are there?
Three: false, normal, and good. False and bad are the same ending.
What do I need for the true ending?
The Four Virtues, then The Self from the Doppelganger, with The Self's Works of Mercy finished.