This is a good question and I'm interested in the answer too.
I know that Sephora and Nordstrom have a no-nonsense return policy but I always thought others would refuse to take back an opened item (unless it turned out to be fake, etc.). I did return a bottle of Zino that I thought was a knockoff to an e-tailer and got refunded. I think you'd be able to do it.
I know that smaller businesses won't take anything like that back.
Does anyone know how the Scent Bar/Luckyscent or Aedes deal with that issue?
Also, I was recently told by a friend that an SA at Macy's told her she can absolutely return an opened bottle if she didn't like it (up to a few months and that "people generally don't know about this"). I'm really surprised at that.
This didn't used to be the case for CD's, computer games, etc.
Recently, I saw an open bottle of Tom Ford Private Blend returned to a Nordstrom that does not carry the line at that location! Honestly, if I were a retailer, I'd have a problem with it but I'm the consumer...