Playing devil's advocate here…
Indeed I think there are better ways to degrease traps, especially at $3 per gallon for gasoline. And yes working with an open container of gasoline can be dangerous but… There is no qualitative difference between soaking traps in gasoline to degrease them or soaking traps in a petroleum based dip, thinned with gasoline. And a number of people use dipped traps even at canine sets, there is no special oil-well set needed to use these traps. As for disposal, gasoline is very volatile it will evaporate quickly. And I don't really see how evaporating a gallon of gasoline is much different than running a gallon of gasoline through your car.
-- Hal