Four (five depending on how you want to count themvape able and had moments where flavor is decent. Other times is weird. Definitely sour which I like. But sometimes flavor gets lost
1. Poor mixing. Failure to thoroughly blend ingredients. May be caused by inadequate initial mixing, and/or, inefficient time to blend (aka. "steeping"). Poor mixing will lead to "hot" and "cold" spots of specific flavor notes. Shake the heck out of it and then shake it again. Practice patience, if it doesn't taste good today, put it away for a few days, and taste it again.
2A (2A & 2B are interchangeable in my mind). Device (dripper vs. tank, AND specific appliance). If you change equipment (attys, mods, or batteries(and their charge)) the flavor will vary too. Any given e-liquid will taste different based on whether I am vaping it in one dripper or another. Let alone if I am trying to compare it to the way it tastes in one of my tanks. Throw in a different coil set-up and all bets are off! "Wide bore," "tight draw," "chuff cap/tip," small chamber vs. large chamber, bottom-airflow vs. top airflow, all affect the way an e-liquid will taste. Mix to your gear, and don't change your gear, while you are creating.
2B. Poor equipment maintenance. Dirty/gunked-up coils will lead to bad/ "off"/inconsistent flavor perception. Clean, or replace, your coils. Whenever in doubt; replace your wick(s). (This is one of the things that lead me away from factory coil-heads/cartridges, and toward rebuildable attys, so I felt better about rebuilding them as I felt they were needed vs. when I felt I got my money's worth (or could afford it). I can't make (and don't particularly have the interest to do) all the fancy, beautiful, uber-detailed, high-tech, coils that dominate certain vaping interests. But, I have found a basic wrap that is easy, and works for me, and so that is what I stick with. I still like to occasionally play with a "custom" coil/build, but never when I am working on a new recipe. For that, I stay with a tried-and-true, repeatable, cost-effective basic coil.
3. Temperature/Airflow inconsistency. Cloud-chasing is easy (relatively speaking); "higher (temperature)" is almost always "better." The same is NOT true for flavor enthusiasts. Depending on the coil configuration, method of wicking, air flow, preference of inhale (mouth-to-lung vs. direct-to-lung), and frequency of inhale; all of these will influence how any given inhale might taste.
The big take-away here (for me; at least) was, and still is, vape/inhale consistency. without changing anything about my gear, or power supply (voltage/wattage), I can make a significant change in perceived "taste," simply by how often, and/or, how long I inhale on any given "puff." A short (+/-) 2 second puff will taste significantly different than a (+/-) 15 second drag. Likewise, if I hit the vape repeatedly, verses letting it cool down in between puffs, it tastes different.
4. Environment. Other things affecting taste, like brushing your teeth, eating or drinking foods/beverages with strong tastes, will change the way an e-liquid may taste at the moment. Avoid other strongly flavored foods and beverages when initially evaluating a new e-liquid. This includes tooth-paste, mouth-wash, heavily spiced foods, alcohol (yes: that means beer, wine, AND cocktails!), soda/pop, and anything that tends to linger (sorry; that means Doritos, and Cheetos are "out" too!). Water, bread (no; no butter... it coats the tongue), or water with a lemon slice, are all considered "good" palate cleansers.
I wish you great success as you venture forth on your DIY journey. The best advise I can offer (that you have already received
(NOTE: I only consider myself a a DIY "cook." Give me six ingredients, and a smidgen of latitude, and I will reproduce something as good, or better (well; at least to me), than the original. But, give me six ingredients, and no direction, and all I can guarantee is a mess with a 1% chance of brilliance.

After 2 full years of DIY, I still consider myself a "Newb," so take what works for you, and throw the rest out. I am on the high side of 50 years old and long ago stopped believing my own baloney. You will not offend me. All advise offered is only "to date... and subject to change (at the drop of a hat)."
Best wishes!

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