colleges tracking social chatter?

Right now as i speak, there are colleges getting applications from people in high school and immediately looking at there facebooks, twitter, etc. my perspective on this is that it is ok. being a high school student you should be smart enough to not put stupid pictures up or stupid posts. this could very well make a college throw your application away without them looking in depth to it. you never know who is actually looking at you, it could be anyone around the world, possible cops and whatnot. all kids just should be careful on what they say.