During the somewhat inconsequential hoo-hah about the disgusting state of recently discarded England wicketkeeper Matt Prior's cap, I was struck by how similar it looked to my battered and venerable Nike golf cap. There was a time when they looked even more similar, even down to the salty sweat tidemarks, but a couple of rounds of golf in rainy conditions of late have given mine a bit of an inadvertent wash. The faded (and, bizarrely, slightly pink) areas still give you the general idea of where my corrosive (and possibly slightly pink) sweat has seeped over the years. Note that both Matt Prior and I have foreheads that are slightly sweatier on the right side. Something to do with being right-handed maybe?
Note the overall similarity in the patterns - basically you sweat into the internal cap-band and that then spreads out by capillary action up towards the top of the head and out towards the front of the brim.
Since I strongly suspect Prior's England career is now over, his cap will presumably be getting sealed away in a trophy cabinet somewhere. I reckon mine is good for another decade or so at least before it disintegrates.