> The other two 'issues' were out of the blue.  The
> Cherokee I trained in used mogas.  I never noted
> excessive smell, and my flight instructor said it
> kept his plugs clean.  The issue with stale gas has
> some credence due to my observation of some
> ultralighter who religiously dump 30day old
> two-stroke mixes.  What I didn't get was how 100LL
> smelled any better or stored any longer.  

   For what it is worth - and I've been smelling gasoline
since the first day I set foot in my father's filling
station, in 1949 - old, stale gasoline (stuff that's been
sitting stagnant for more than a year or so) does smell
really bad.  Kind of sickly sweet.  And it's darned near
useless as auto fuel - except if diluted with fresh
gasoline (and it probably doesn't yield full BTU's then).