And to expand on sistrum and dagmar's posts:
I've saved a bar from every batch since I started soaping and I try them out from time to time and keep notes.
Yep, I literally use them every 6 months or so; let them air dry and then put them back into my private stash!
After 3+ years, I haven't had any rancidity or DOS, but some of my FO's have disappeared or morphed into something less than pleasant over time...this is yet another of the things I feel I NEED to be aware of as I slowly make the move into selling!!
I'm pretty sure I'm not the only one on this forum to ever read a scent description of a soap from an online soap vendor and think, "Wow, that sounds divine...gotta get that one!"....only to recieve a bar of soap that smells of nothing but 'old soap' or worse. I'm pretty forgiving and I always try to give sellers a second chance (esp those whom I really like the IDEA of their soap); thinking maybe that 'that particular scent' wasn't to my personal liking...but some vendors fail the second chance as well. Granted they got my business twice, but never again.
To paraphrase dagmar: 'That's why I test."
I don't want to be one of THOSE sellers...I want the first bar of my soap you purchase to be so addictive that you can't live without more of it AND you tell all of your friends about it.