I have several things that I keep around because I sometimes need them for my bakery business. Or because I just haven't used them up completely. Or haven't thought about throwing them away. Or whatever. It's fairly easy to tell which things are artificial flavors, since they usually SAY "imitation" or "artificial" or simply "flavor" (e.g. strawberry FLAVOR, almond FLAVOR, butter FLAVOR). Not the real thing, just the FLAVOR of it.
A good clue for vanilla? If it's clear, it's not real vanilla... At least, not that I'VE ever seen...
If you're looking for the real thing, look for "extract" or "natural" or "natural oil". Watch out for things that are "made with" real vanilla, et al. That means it's just part of the ingredients, not that it's totally natural. "Double strength" varieties of vanilla are big offenders here, as they will sometimes make real vanilla, and then add the fake stuff to make it "double strength". Ask me about discovering that AFTER using it in my food... That'll teach me to read the labels... *sigh*
So in visual summary of my cabinet:
Interesting note: Did you know that Wintergreen oil is sometimes manufactured in a lab, and then marketed as "natural" because it is molecularly the same? Just something to think about...