Good topic! Thanks, Chefbrent! I have also experienced some juices that didn't seem to change over time. But I've found that most of them do.
The most recent example I can think of is BWB's Malty and Malty Toffee. Those two are so popular, that the vendor usually limits the number of bottles one can purchase for each order placed.
I luv BWB! I have tried more than a dozen of their flaves, and all have been to my taste, the day received! ... Except for Malty and Malty Toffee. I received them last August. They were not bad; they were not good. The problem for me was that they weren't ANYthing. Bland, tasteless. Not offensive; just neutral and flavorless.
[Except for one cig relapse, earlier this year, I had not been smoking for over a year; so I really don't think it had to do with taste-bud adjustment -- which is a legit issue, for a good long while, after one first quits smoking.]
Well, it's now 3 months later. While organizing my stash of liquids, I find Malty and Malty Toffee buried there. I give each a whirl. And HOLY MOLY! They changed!!! FINALLY, I understand why they're such top-sellers!
This has happened with quite a few other liquids I've purchased over the last 18 months. However, I do have to once again concur with you, that there are a lot of liquids that just are-what-they-are, from day one, to year one. Enjoy the journey!