Hmm... My opinion on dupes lies somewhere between all of yours.
This is my first time ordering from pp, but like Artdeco, I don't feel bad ordering a dupe of a big brand (Dior, YSL etc) perfume. I agree that most of the £££ goes on ads and celebrity endorsements etc. I also think they have reduced the quality of the ingredients used to increase profit margins, so I don't feel like my money is going where I want it to, ie paying for the perfume.
I wouldn't order a dupe of an independent/niche perfume, as I think (but don't actually know) that they use better quality ingredients, have better ethics, and mostly try to keep their products reasonably priced (at least in so much as the price we pay more accurately reflects the cost of the ingredients/labour going into the actual fragrance, rather than into creating hype). I want to support that.
Somewhat like Judy, I would never wear or use fake branded clothes, bags etc, partly due to disliking obviously branded items, but mainly because I think there is a difference between perfumes and items like clothes, shoes and bags. To me, perfumes are consumed a bit like food. Particular 'flavours' do not belong to anyone, so neither, I think, do particular 'smells'. The dupe isn't in the same packaging, calling itself the same name etc, so it's not a fake to me in the same way as a knock-off bag would be. I would never buy fake branded clothes, because in my eyes that is a kind of deception, and I would feel like a fraud. If pp, for example, called a fragrance Chanel No5, and used a copy of Chanel packaging, I wouldn't go anywhere near it.
However, I also agree with MrsR (your description of Lpdt is really beautiful, by the way). I don't think I could buy a dupe of my absolute favourite fragrances, even if they were from big conglomerates, as I would feel terrible, as though I had somehow betrayed someone or something. I do realise this is illogical and contradictory, but I suppose that's because I have a quite emotional connection to my favourites.
Also, having said all of the above, I do secretly enjoy the 'experience' of walking into a department store perfume hall, seeing all of the counters and bottles, testing this and that, and interacting with the sales assistants. I also quite enjoy receiving beautiful bottles in luxurious packaging.
Anyway, that's just my opinion on dupes. Perfume is such a personal thing, everyone will feel differently. Having read through my post though, I'm sure I sound quite irrational. 🙈