My assumption has always been that they come back with a score, show the studio, and the marketing department takes the guy from Famitsuu into another room, where they "discuss" it. In my most cynical versions, the Famitsuu guy takes out a little menu, with +1, +2, and +3 on it, with a little price next to each of them. The prices are exponentially more expensive. I also assume there's a +4 that's not on the menu, with a price tag only SQUEENIX can afford.
Oh, there's also the "Please delay the publication of the review" menu item, which is a freebie provided you also pay for one of the others. This is the only way I can explain the 32 or 33 Dirge of Cerebus received on a review which came out something like 3 weeks after launch.
Q: When does a Square game EVER get late attention from Famitsuu? A:
spoiler (click to show/hide)
When they request it.