Our rental unit has a recently done marble bathroom (don't ask...). Marble needs to be "sealed". OK fine.

One of them has come up with the idea that they needs this $1000 (!) service to come do it. They're not rich, neither are we. Seems to me all we need is to clean it (there's no stains or damage) and wipe on a sealer.

I believe this "service" is a bullshit ripoff. I have no experience with this stuff. But I can't find online anything convincing, since it's a negative-information I need, it's difficult to search for.

What possible thing need be done to marble, other than clean and wipe on a sealer?!!