This is a good example of the type of scientific caveats you need to worry about when you run an experiment. Chances are, your experiment will tell you something, but it won't tell you the full story, and if you drill down further you'll discover something else that's more accurate but probably a less sensational headline.
The essence of the problem is in the generalizing of the conclusion. The experiment will rigorously demonstrate something utterly abstract and then the experimenter will make huge intuitive leaps when interpreting the results.
I have found this to be the most overwhelmingly common flaw with experiments reported by mainstream journalism, particularly those in the field of psychology.
The experiment will rigorously demonstrate something utterly abstract
Actually, the "average faces are more beautiful" claim hung up on something very specific (skin tone). I think it's small details that aren't controlled for that often invalidate the more abstract conclusion of psychology experiments.
