I really have no idea.
I know that there's always some concern about people gaming the hotness charts. Even though I'm not really sure what the end game of that would be. I guess as a form of "marketing" to make it look like your game is really popular. But it just seems sort of variable; but I admit it's nice to have a series of "quick links" over there where there's a certain meta-society-gestault thing about a game...if you use bgg as a reference, in general you are learning about a game at the same time as everybody else.
But as an interesting example on the rpggeek side of the site, I have put up a new Fiasco playset. It's called "Lord Doomicus and His Giant Battle Planet". It's a playset designed as a comedy about all of the background people who are needed to run a giant Star Wars-like Death Star.
It "became active" yesterday. This morning, it's rated number #2 on the "hotness" scale, behind the Star Wars: Edge of the Empire game. I checked the Giant Battle Planet direct link and it has had....32 views, with 18 downloads.
Again, this is on the RPG hotness scale, and not the boardgamegeek scale. I assume it takes a lot more than that on the boardgame side. Bu, then again, I could be wrong about that.
I don't know what kind of traffic drives the rpggeek site on a given day, or if the RPG world is consumed by 3 or 4 800-pound gorillas (such as D&D and Pathfinder) with everybody else a quite-the-distant second, but I just find it interesting that that small amount of clicks on that side of the site can drive something that high on the hotness list.