What causes that is bad fuel , when the petroleum based fuel already has water in it. When it's blended with ethanol, it causes that water to precipitate out of the fuel. So if anything, ethanol is a good- "bad gasoline" detector. If the gasoline is good when ethanol is blended, say e10, any water entering the fuel tank will be ABSORBED by the ethanol, PREVENTING fuel line freeze up. That's why you DON'T need gas line antifreeze when using e10. Plus you get an octane boost from e10, giving you BETTER gasoline performance.
HOWEVER, I wouldn't recommend burning e85 unless the engine has been extensively modified to burn alcohol properly, taking advantage of it's properties. otherwise, you will get poor efficiency and miss out on a tremendous power increase. E10-25 is perfectly fine for regular gas cars however.
Pure ethanol itself can absorb 60% it's volume of water and STILL burn, without water precipitating out.
In fact you drink ethanol blended with water in even higher ratio's than that.
have you EVER seen water precipitate out of your whiskey?
Nope. I spoke specifically about marine and aircraft engines, not new automobile engines. Everything I posted about ethanol use in aircraft and marine engines is absolute truth and it's being widely reported by not only the AOPA and the EAA, but the FAA, too, with scientific data to back it up. Several boating organizations are also warning of the pitfalls of using ethanol in marine engines. Do some research. Here is a direct quote from the AOPA regarding ethanol use in aircraft:
Ethanol deteriorates seals in aircraft engines, harms fuel bladders and hoses, and attracts water, which promotes rust that can damage cylinders and pistons. It also can lead to problems in electric fuel pumps and cause inaccurate indications on fuel gauges, according to studies by the FAA.
The rest of the article can be read here:
http://www.aopa.org/whatsnew/region/2007/071129or.html
Pilots regularly "sump" the tanks in the aircraft to determine if there is water in the fuel prior to flight. This involves drawing a small amount of fuel from the lowest point in the fuel tank, aka, "the sump." Aircraft fuel tanks have these sump drains installed and are mandated by law for this very purpose. Sumping the fuel tanks is part of the normal preflight inspection of the aircraft prior to flight. The problem with ethanol in auto fuel that is inadvertently used in aircraft is that it hides the moisture. Sumping the tank won't show whether water is present in the fuel if ethanol is present. Regardless of the source of water in the fuel this is a life or death issue for pilots that run auto fuel in aircraft. The same could be said for those who operate in blue water environments in boats.
A simple ethanol tester sold by the EAA, among others, is nothing more than a test tube with graduations marked on the side for gasoline and water. You put a predetermined amount of gasoline and water in the tube, shake, and wait 10 minutes. If the separation line between the gasoline and the water disappears, i.e., the ethanol absorbs the water, then there is ethanol present in the fuel. Graduations are marked on the side to show whether the concentration is 5%, 10% or greater. Essentially, what happens is the amount of fuel in the test tube appears to increase.
Further, most reciprocating aircraft engines that are currently flying are not suited to ethanol use whatsoever. The carburetters on thee engines do indeed have seals and needle seats that are affected by ethanol. The same is true for fuel tank bladders and some types of synthetic fuel lines. Don't take my word for it. Read what the FAA, AOPA and EAA have to say about it. Ask any A&P mechanic and you will see that I am right on all counts.