Well, you see, they're very thorough. They believe in fully investigating a serious matter like this before jumping to hasty conclusions. A mere perusal of our daily television transmissions, for example, has given them the general impression that we are probably all violent, silly, and insane, but they have held off destroying this planet as a galactic cautionary measure for the time being, because they don't want to be too precipitate. They figure, reasonably, that there might still be something or someone worth saving here. Like me and Winona Ryder, for example. And Dachshunds. ;-)