I'd recommend they stay the fuck away from earth, and humanity in general. I mean, everything we try to fix, causes another problem (we build cars, we get global warming -and/or- we build homes, we get de-forestation). We fight over anything (religious militantcy, anti-relgious militantcy, eco-terrorism, economic-terrorism, you get the picture).
So yeah, Earth and humanity pretty much suck. In fact, if we had any real sense, we'd re-name this place "Suckage". But we don't, no one does. [/emo]