As a chemical engineer with 35 years experience in the oil & gas business (including some refinery design), I am quite comfortable with my knowledge of gasoline chemistry.

All liquid fuels can get contaminated, with dirt, condensation, whatever. Camp stove fuel filters are light and cheap, and are a good idea regardless of which fuel you choose.

Still, the fuel requirements of a camp stove are not even close to those of an internal combustion engine, even one in a brand new 10-year old Pontiac. Camp stove fuel gets squeezed through a little hole (an easily cleanable hole) and burns at atmospheric conditions. That's all there is to it. There is no rocket science involved, no fancy fuel specs to meet, just the opportunity for someone to get you to part with your dollars faster than you would otherwise. (Sort of like selling tap water in plastic bottles - some people will pay for it).

A while ago, db suggested two litres (or so) would be enough for a two week trip. If you take two trips a year, and save $5 per quart by buying regular unleaded, then you can buy a new stove every five years with the savings. But of course your mileage may vary.