I'll start with skinny co pornstar martini mix. Tasted incredibly sweet and synthetic. It stated use 1 part vodka to 3 parts mix. I tried that too sweet added more vodka so 50/50 just about drinkable. I drank another one with the reverse ratios, almost OK but I was so drunk I fell over and knocked the TV over.
The other downside was that it stank so much so that my empty glass had made the whole room stink.