I think it's hard to define a 'signature scent' for me as what someone else thinks of it, or if it reminds them of me. BO could be a signature scent for some people. I get that definition, but it's not the connotation I give the term.
To me a signature scent would
- be something I enjoy smelling
- be something that I feel complements and/or defines who/what I am; a soul-completing sort of thing
- be something I could wear every day and be happy
- be something I own and continue to refresh/purchase as needed
- be something I *do* wear in the absence of reasons to wear something else (e.g. trying something else out)
Ultimately, it's about being completely happy with a scent. Not to the extent that I give up sampling other things, but in a way that if I'm undecided or not caring about what I wear on that day, or hyper-sensitive on what I wear, it still always comes up as a top choice.
And that's not to say it needs to be just one perfect scent in a world where there can be only one. This isn't marriage.
As it is, I don't actually use the term "signature scent." I rather just have a list of my favorite go-to frags. Or, even more basic, a list of likes, dislikes, or neutrals.