You don't get ear infections from the outside very often (it is sealed by the tympanic membrane). Think about all of the stuff that ends up in your ear anyway. He may be "cheap" but not "retarded". I have used one headphone from my Ipod so that I can still listen to the engine which is helpful to hear the engine still when shifting (ie:motorcycles) but with snowmobiles it shouldn't matter. I am going to try both ears next time. Also in regards to hearing your engine, when you get used to the plugs you can still pick up differences in your engine, it is just quieter.