Why?
Why can't they learn to tell the press to go away and leave them alone?
Because they want public to know the results of their experiments. I never said that scientists were particularly skilled with dealing with the public (in fact, I've said that they're pretty bad at it). As mentioned before, scientists are in general very good at conveying information to each other, but not to the general public. So it becomes sort of a chain.
1. Scientist gives accurate, but complex information to a not very well informed person who is hired to write a press release.
2. Person writes press release, but isn't nearly as accurate as what the scientist said, either in a failed attempt to dumb things down some for the general public or the person just doesn't really know what he is writing about.
3. Reporter reads press release and does the same thing as the person who wrote it.
This is when scientists and research groups should be saying "hey, maybe we should be better at writing press releases or at least publicly correct what is said in the mass media and work for better science journalism in order to promote greater scientific literacy".
However, they don't. In their minds, they gave someone accurate data. They're not concerned with correcting what the public thinks, they are on to the next experiment. For a large chunk of science, it doesn't matter what the public really thinks as the science has little relevance to their lives or isn't even particularly important in the science world. So it's not much of an issue. However, with some stuff it DOES matter - like global warming, and massive research projects. It's there that scientists fail pretty badly.