Everyone likes to hate on spammers, but they’re basically the houseflies of the Internet. Far more insidious and damaging are astroturfers and front groups—those corporate-funded, agenda-pushing people who don’t disclose who they’re really working for while they participate in online culture and the media. The Center for Media and Democracy has put together a list of tips to help you identify them from real grassroots movements, while Free Press has created a widget that reveals front groups for five large companies you frequently see on Consumerist.