Do you mean stuff like that found in grocery stores? McCormick's and such?
There have been some comments around here that McCormicks flavorings (and most general grocery store extracts) aren't concentrated so may need to be made with quite a lot of the flavoring. Some find it "tastes like ..." to quote a thread. But some people have found good flavors.
Extracts may also have a lot of alcohol, which often is too strong tasting to
vape.
Note that may here think that vanillin, artificial vanilla, is not safe to
vape.
Personally, I have avoid McCormick's for many year. I just don't think they taste very good in cooking - I certainly wouldn't want to vape them. I stick to LorAnn, Bickford, Capella, and Faerie's Finest. I plan on adding FlavourArt one of these days.