Yes - 22%
When I announced this poll a month ago on both my Twitter and Facebook, I received a few confused reactions along the lines of “Why would anyone skim the foam as their wort comes to a boil?” Despite less than a quarter of homebrewers responding that they do, I think there are a few advantages that are enough to justify this small/optional brew-day chore.
The more protein the wort contains, the more foam forms on the surface of the wort as the temperature approaches 212F (wheat beers tend to produce an especially dense mousse-like foam). While some people refer to the foam as “hot break,” traditionally/technically this term refers exclusively to the flocks of protein seen floating in the boiling wort (for a good picture of what this looks like, see my batch of spelt saison). I’m sure the Germans have some cool word for the foam, but it hasn’t been given a special name by American homebrewers.
Skimming reduces the chance of a wort boil-over in two ways. First, removing the coagulated protein foam reduces the sudden rise at the onset of the boil that within seconds can lead to wort bellowing over the sides of the kettle and onto your burner. Skimming also forces you to stick around the kettle as the wort comes to a boil, so you’ll be there to turn down the heat if necessary. Alternatively you could add an anti-foam product like Fermcap-S (which I don’t care for) or use a spray bottle of water to deflate the foam.
Skimming does not have a negative impact on the head retention of the finished beer in my experience. This is because proteins are only capable of coagulating one time (Don't believe me? Try to return a hard boiled egg white to its uncoagulated liquid state.) so the proteins you scoop from the wort would not have assisted in head formation. However, if you use a mesh strainer that serves double-duty for anything other than skimming wort, then make sure it is scrupulously cleaned because it doesn’t take much oil to seriously disrupt head stability.
I don’t skim every single batch. For example, when I add first-wort hops skimming would remove the hops before the boil. This rule also serves for any batch where a solid ingredient is added to the wort post-mash, but pre-boil. Otherwise I’m a skimmer (unless someone posts a good counter-argument in the comments).