Scientific fraud has always been a problem. People claiming to have discovered something, when they know they really haven't, have fooled many people many times. (See history of science). Scientific fraud differs from scientific error, since in the case of fraud the researcher knows his findings aren't actually supported by the available evidence.
Major organizations which promote or protect fraud
An American Association for the Advancement of Science (AAAS) report defines scientific fraud as "including falsification, fabrications, selective use of data, and manipulation of graphs and figures."  Ironically, the AAAS is itself guilty of selective use of data and of censoring papers which contradict its public policy positions.