The quick vg test is to buy a small bottle of glycerin usp in a pharmacy, clear bottle, likely says skin protestant, and the only ingredient is glycerin 99.5%. Six ounces is about five dollars.
Put some in a small bottle, cut it with about 15% distilled water, shake and try to vape. Go slow, if you feel any effects stop.
Same can be done with pg, just don't need to cut it with water and it is not as widely available at normal stores.