Just a quick answer why those things are true: because.
But I don't think they're true. I think all those words are applied equally to cheap, expensive, or even middle range scents. I've seen the expensive brands accused of ripping off scents plenty. I think all those words can be or are synonyms for each other and which scent a person prefers probably dictates which other ones get that person's pajorative words. I could rather ask you: why do you think copied and ripped off and reworked are only applied in the ways you suggest? I think it suggests how YOU think the relationship between expensive and inexpensive brands comes out.
But, as if this is only a quick question that you need someone to answer, and as if there is a quick answer easy to relate, my anwer is my first one. The answer is because.