Whether it stains, whether it can be painted, and what an old floor can be made to look like.
21 questions in this harvest fall under this subject. 2 answered so far.
Sealed, it resists most things quickly wiped up. It does not resist acid, and acid is not a stain — it dissolves the marble aggregate and the cement matrix and the repair is a full diamond grind. That is the whole answer in one sentence, and it is the reason the sealer and the cleaning chemistry are quoted together rather than separately.
Find out what the stain is first, because the wrong product makes it permanent. Acid on a cement matrix dissolves the surface — it is not a stain, it is a loss, and no polish restores it. On a sealed floor most marks come off with neutral detergent; what does not come off is usually pigment that has entered a matrix which was never sealed.
These are the phrasings people typed, not headings we invented. Where one has an answer the link is live; where it does not it is printed plain, and that is deliberate — a printed question with nothing behind it is an honest promise, and hiding it is not.
Ordered by how many questions each one holds.