Tools/Website/Service to Analyze Blog Posts et al. for Robotic Origin

While reading posts on slate.com I was struck how many were similar to past posts I've encountered. Certain memes pop up repeatedly (usually denigrating the OP) and contain no useful information. Of course people copy one another's writings and style, but it occurred to me there might be websites or analysis tools that would tell me whether a post, or which posts, or a statistical analysis of posts likely to have been generated by a robot. There's probably a vocabulary and an entire work milieu/domain/subject area about this topic but I am naive. Can anyone help me here?