I don't understand why everyone keeps saying VG has no throat hit.
The people who mixed your VG didn't do it right. That is all there is to it.
Certain FLAVORS have more throat hit than others. VG has less chemicals in it so naturally it is safer and may have less throat hit than PG. If you bought 36mg VG and it didn't have throat hit, it was not 36mg. If you bought 18mg VG and it had no throat hit it was not 18mg. It was probably 4. The strength of the nicotine and the flavoring is what gives you throat hit with VG. Certain flavorings have alcohol in the ingredients. If someone messed up your juice you can add everclear or a higher strength nicotine solution to try to get a little more throat hit.
Nicotine=throat hit
Other chemicals that are bad for you=throat hit
Certain flavorings=throat hit
Alcohol=throat hit
I compare a marlboro red to 36mg of nicotine, although in realty a real marlboro red is probably much less, but you have all those bad chemicals in a real cigarette.
18mg is weak. Only new users think that it is strong. Try vaping 24mg vg or even 36mg vg. If you cut your juice with vg, you weakened it.