sorry about digging up an old thread, but this came up on google and wanted to add my 2c.
Xrated is correct, it does suck it out of the air, also at the fuel station the tanks fuel gets moved, it does not remain stagnant. some stations have mixing processes, some just mix when the tanker tops up the tanks daily/weekly/monthly depending on the popularity of the station.
it doesn't matter what fuel it is really, any fuel sitting 'stagnent' for too long becomes bad and stabilizers are required. apparently E85 is a bit more volatile (like methanol) than other bowser fuels and as such has different characteristics. there is some good information on the internet like the U.S Department of Energy's release on storage you can find here ; http://www.afdc.energy.gov/uploads/publication/ethanol_handbook.pdf
like for example; my brothers VL was parked for a few years with 98 in it.. eventually the carbon separates and creates black silt everywhere which seized up and killed the almost brand new 044, which was left in it. now if he had used a stabilizer it may have been a different story, however I am not sure if the 044 can sit like that for that sort of duration and then work no idea about that but in this case it did not and we had to pull the entire fuel tank out and clean it and replace the pump, it was f*kt.
also on the moisture, E85 isn't the only one that does it, infact many years ago when we all used to play with carbys and v8s, with leaded fuel, we used to have to run water seperators/ w filters on the lines, so the carbs would run right as we would end up with water in the fuel as all the tanks were steel or alloy because not only was the fuel absorbing moisture on the muscle cars as they would sit for long periods, but the tanks would get condensation.
ps. no road car tanks are completely sealed, they all must have a breather.