I have seen the good efi hose and the injector hose turn a light tan color, and a white color on the inside. The cheap carb hose doesn't last. They make ethanol hose that last longer, but still eats it. One thing I have noticed is that the tygon hose for the bleeders to the mains etc, I haven't seen an issue with that hose.. It gets a little hard over time, but the inside looks good...
I run ethanol in my chainsaw, and weedeater with aces and it sits for a 6 months sometimes. Haven't had an issue yet.
Roy