should not exist. period.
you can't get the flavor out if you've stained the hose.
i've tried everything from compressed air,
to smoking an ass-load of mint shisha,
to putting it in the fridge.
these stupid things shouldn't be around anymore.
if you get them in the water, they're history!
if you like in a high humidity climate, your hose is ruined.
washable hoses are perfect because you can wash out any old "stain-flavor",
there's not a metal coil which makes it more flexible,
they last longer,
and they are more pleasant to smoke with.
the only bad thing about a washable hose is that they tend to cost more, which in the long run is a good investment.