This is interesting and something I'm just discovering.
I have a bottle of zero mg, and a bottle of 6 mg - both are the same maker, same flavor, and same birth date (of course same steep time).
The one with the 6 mg of nic is more than 10 shades darker in color and the taste and aroma are much stronger! What I've learned from this is that adding nic to juice, at least in some cases, does more than give you nicotine or add a little bit of a "peppery" undertone to the flavor.
Very interesting Vwls. I know nic degrades much quicker than anything else in our juices and I'm thinking that may be the reason for the quick darkening, but I certainly don't know that for sure.
I make my own juices. I've been adding nic only to my one dark juice since I went back to using it a couple of months ago because the taste change is really good for that one. It's also a significant change in taste (for me) at 5 mg. I'm going to try spiking one of my clear juices next time and see if that causes color change. The clear stuff does not change at all now, well at least not over the month or two it may sit around before I vape it all.
Taste is also complicated. You can add one flavor to another and they don't always become exact combinations of each, but can turn into something different. Plus device choice and power settings change taste too, bringing out different flavors. And you also don't know if the two juices that are labeled the same are mixed the same.
Lots of variables in this picture, but then what else is new
