Both sides of the aisle are guilty of this:
Bogus Grass-Roots Politics on Twitter - Technology Review
I took a class in network theory and system of systems modeling. Basically, by correlating similarity in twitter posts and noting unique personality traits and linguistic quirks that individuals have, then filtering out the ones who are honestly tweeting versus who is merely parroting language wrought forth by their special interest overlords, we see that many times individual accounts in Twitter really aren't being written with individual thoughts but instead of similar tweets to others.
Naturally one will say a certain amount of data is corrupted, since hot topics are hotly discussed and people will naturally cluster together on issues, but if you take into consideration
time and how often tweets appear in relation to each other, and track how much other uses quote others, you find a striking conclusion that there are a core group of people for any particular idea that is hot at the time stimulating a group of people who are their target. This results in a very effective mirage of "grass-roots activism" that many people these days are fond of.
In simple english, "don't always trust what you read" , or in this case, read in your twitter feed.
As an aside, it is fascinating how Twitter has become sort of a torrent of data for human moods and emotions, with some people claiming you can predict stock market movements based on the mood of investors and the frequency of certain keywords.