There are sweetners in a lot of e liquids, and it is virtually impossible to find out which ones. I avoid artificial sweetners in food, but that's easy because you can read the label.
So far as I can find out then most dessert flavours have them for sure, and chocolate flavours need them, because raw cocoa is unpalatable unsweetened. (you can't use a lot of real sugar in e liquids, because they would ruin your attys.)
My current favourite sweet type flavour is DV real banana. It states that it is 100% natural. I take it on faith that that means no sweetners. I vape it vg, which gives it some sweetness, and it has no artificial taint that I can taste.
All I can suggest is that you research the individual companys that make the flavours. You won't get an a-z ingredients list, but you will get a general idea of their ideals generally.
LF cares about the products they are selling, and pride themselves on quality, but they can't give you a list of ingredients that their suppliers don't release. I am absolutely sure however that all of the mainstream companys producing flavours for e cigs care about the safety of their products, and are not adding the long list of known poisons that cig producers routinely add.
I hope that this is of some help