Re: flip-flopping on coffee, eggs, etc. It really depends on which industry funded the study.
"Researchers" capitalize on the public's ever-declining science literacy. Cholesterol is bad, eggs have lots of it, therefore eggs are bad. Sounds logical - but it's bad logic. It presumes that the cholesterol in the eggs goes straight into your blood, which it doesn't. That nasty cholesterol clogging your arteries didn't come from eggs or bacon, you manufactured that goo yourself!
I can't remember where I read this, but I saw somewhere that manufacturer-sponsored drug tests were 4 times more likely to verify positive benefits compared to government-sponsored studies. Check out a documentary called "Orgasm, Inc.". It will open your eyes to the reality of pharmaceutical chicanery. To the topic, it illustrates how to manufacture lies and back them up with "scientific" studies that are not truly scientific at all. Unless you can call Marketing a science.