As far as I can recall, I was the one who tested lemon juice and the effects it had on fruit flavors. At the time I was also using sucralose (ezsweets) in fruit/bakery flavors. I also tested distilled vinegar (not acv, I dont use it) on tobaccos.
What I found with fruit and bakery vapes is they were great initally with the additives, for about two days. Then on day 3 like clockwork the sharpness/crispness of the flavor was just... plain... gone. It never rebounded either. It just continued decline. So I started testing the same juices with lemon juice and sucralose separately. Trying to find the culprit. The result in my tests was that they BOTH decrease flavor output of ejuice. While they help initally boost and sweeten flavor, within a few days, they both cause ejuice to simply go flat. While its a more dramatic example, I feel the same way about ejuice with lemon or sucralose as I do about flat soda pop. Its just lackluster.
This occured in both high VG bases at 80% and high PG bases at 80%. I tested both because I didnt want people calling me out saying VG mutes flavor, which to this day I refute as utter nonsense.
I no longer use either in any of my mixing. I have found that using fruit flavors with alcohol bases provide more than enuff sweetening o. their own if they are steeped for 48-72 hours, and it helps that I use 80%VG in my juice.
As far as tobaccos go I also agree vinegar that after a few days it can flatten flavors over time. However!!! As I vape mostly tobacco ejuices I still add 1 drop/5ml of distilled white vinegar to my vapes. To counter the flattening I adjust by adding slightly more flavoring. About .5% to 1% more flavoring in a final mix. In my experience this counters the effect of flavor flattening with DV and allows mostly all tobacco vapes to round out immediately. (note: i also heat steep my juices at a constant 150° in a water bath in a crock pot for four hours after mixing and have found it it adds about 2 weeks to the aging process of ejuice). At the 2 weeks mark (in my case then this is 4 hours after mixing), all of your tobacco flavors will have a spike in flavor and will stay there, but only round more given time. Giving you a spiked up flavor but still rounded body to your vape. I found apple cider vinegar made bad and good juuces worse with no spike at all, but to be fair I barely ever tested acv.
All of my vapes... yes read that as ALL... are primed and full bodied in four hours. Period. Ultrasonic isnt the answer either. Hand shaking is enuff for juice. Heat allows flavor dissipation and release FAR FAR better.
Alot of what I do flys in the face of common and well "documented" processes others use like ultrasonic steeping tho. (if it works for ya, great. I know what I know and heat is the key, not vibration. And yeah, I tested that too about three months ago so I stand behind it).
People just pretty much ignored my testing. I took painstaking measures to control the samples and.prove to myself the results. Today when people say they use lemon juice, or sucralose and RAVE about the results.... I know they are NOT
vaping stellar juice. They are absolutely, positively, better off without both. Unless they are going to vape what they make in under two days.
Note: I did not bother testing the effects of citric acid powder in juice, but I assume it has the same effect as lemon juice and mutes flavors.
We'd used 9% saline solution in our VG Base (VG, dw, saline, pga) for almost a year. With the Nextel we could taste the salt for the first time (in some mixes), and others (particularly the sweeter ones), seemed to lose intensity (which is the effect of the salt even though we couldn't taste the salt). 
