"What's a Spyborg?"
"Oh, about a buck fifty."
Get it?
Edit: I think SpyBorgs didn't sell because there's nothing interesting about it. EVERY consumer would look at it and say "Who cares?" 500 copies is the range where the developers' parents, friends, siblings, and teachers bought a copy of the game, really. No kidding.
As far as Resident Evil selling well? It's new content. There was reason to buy it. It takes an established, big-name franchise, and then gave in backstory and new content. Yes, some of what was shown is the same "story" as what was in a few RE games, but all in all, it's a new experience, created independently, offered as a new game. I reiterate, there's new content, story and gameplay-wise. If I own console X or Y, it doesn't matter, because there wasn't any delay for this, either.
You look at Dead Space Extraction, or whatever it's called, it's one of several things: It's late to the game. Why not get one of the other Dead Space titles on another console? After all, they came out first, and as far as I'm aware, the Wii is essentially the same game, except on rails. Am I wrong? To be honest, I'm not certain if it is or isn't. Who's responsibility was it to tell me otherwise, though? Exactly, that's a marketing problem. To be honest, all I know about the game is that it's a thriller-type game in an on-rails setting. I read early on it was a remake, but I don't even know. Had I bought the original dead space, there'd be no reason to pick this up. It's new content, but the story isn't new, and there's nothing worth visiting if you've already played the first. If you haven't played either, why not get the first? It's the original, and this game is just a method to reach the story out to more people. EA got themselves in a lose-lose scenario here with dedicated console gamers. There wasn't really a "win" scenario here.
MadWorld is a niche title. Didn't it's sales meet or grow near expectations anyways?
What about No More Heroes? There's a sequel underway on that. The new RE game? Developers making mature titles still aren't taking the platform seriously, as a first-tier system. Why not? Because they never did. It's a self-perpetuating system. The developers that did treat it well are coming back, like Capcom and Grasshopper. The ones that never have are still seeing failure. Seriously, that's all it is. No one ever expected anyone to care about Spyborgs, and Capcom knew it was a lost cause. Who knows why they didn't just scrap it, but honestly, it was probably very cheap and very easy to produce, so they just decided to keep going when they realized it would bomb. It's seriously a game that wouldn't sell on any system.