A new study has worked out the effect online comments have on readers - and it's surprisingly large.
The study hails from the University of Wisconsin-Madison, and concentrates on layman reports of science stories (appearing in regular newspapers and magazines). It found that content in the reports were very easily undermined by the comments below  - even when it was a simply a matter of tone.
Authors Dominique Brossard and Dietram A. Scheufele asked 2,000 people to read a news report about nanotechnology. Half of them saw it with balanced comments underneath, and half saw it with vitriolic, name-calling, angry comments underneath.
"Disturbingly, readers' interpretations of potential risks associated with the technology described in the news article differed significantly depending only on the tone of the manipulated reader comments posted with the story," wrote the researchers.
"In other words, just the tone of the comments . . . can significantly alter how audiences think about the technology itself."
Knowing about science didn't seem to make a difference, either - informed readers were just as easily swayed. The researchers warned of the dangers of setting science reporting in an online context, where other people's perceptions are immediately available to us.
Conclusion: don't comment, don't read the comments, don't allow comments. Save the science!