Great topic Malcolm, that's inevitably returned to the OVO vs reissue/boot topic. The simple answer is that it's only a con if there is deception involved. So if you go to an OVO event and someone plays a boot the punters are being conned (likewise for passing off boots as original when selling records).
Are the prices a con? That's a bit more of an grey area in my opinion. On a simplistic level if the seller is being honest about the product then it isn't but on another level if it is the scene's obsession with OVO to the extent that the average Joe is shamed into parting with high prices because of the perception of unacceptability then there is an element of conning. Not by the seller but by the OVO evangelists who make them think that it matters to that extent.
In my youth I used to do 'mixtapes' of tunes I couldn't afford to buy. I think most of us did. But I also bought records from my local shop as far as my budget stretched. These days I have a bit more money so the balance has shifted a bit more in favour of originals but I'm not ashamed to say I will buy a reissue if the original is outside my budgetary grasp. So for example I bought the Don Gardner album to get the 45. When people feel pressured to deny they own boots /reissues or to think it is only acceptable to buy originals I think that's sad and the deception in the scene that they (reissues etc) are unacceptable is verging on a con and pushes up prices which is also sad.
Before I get a hail of abuse from the OVO folks, please let me be clear, I fully respect your love of the originals and understand the collecting obsession. But I would also ask for respect in return of my love for the music no matter what issue I choose to listen to it on. If we could get over this (unlikely I know) then the con of overpricing might reduce because the supply and demand relationships would alter.