As someone who's been familiar with them since before their association with the Republican party, their platform goals are what they typically donate towards.

As someone who's been familiar with them since before their association with the Republican party, their platform goals are what they typically donate towards. Marijuana legalization / decriminalization, marriage equality, cancer research, arts, the Smithsonian, PBS' Nova, open borders, school choice, and free market principles. Yes, they donate to Republicans, and no, I don't know why. Also worth noting, they used to donate to Democrats more than they do now, and most of the 'big names' in the Democratic world (Hillary, Harry Reid, Barack Obama, et al) are recipients of Koch donations. It's definitely possible that they're also spending for nefarious purposes, but I suspect that it depends more on predisposed ideology, or ideology on the role of PACs in society as to whether or not you view them that way.