The idea that a diamond is "inferior" is not one we all share. I personally like lots of different things for differrent reasons. In certain way some out shine another, but beauty is really in the eye of the beholder. You can get a "perfect" diamond, but will pay for it. But depending on who you ask, perfection is varied. AGS perfection is what some people aspire to have, others love "their perfect stone", with character and slightly wonky characteristics.
As for "passing it off"...that is somehting totally different and a vaery personal decision. There are a lot of reasons that people may want to keep the source of their stone to themselves. Asha is made to resemble diamond. If you love how a diamond looks but want Asha instead, it makes sense that you want a stone with realistic characteristic.
Joseph Schubach Jewelers