Don't for me. Not anything unusual anyway. How much nic are you using and how dry is your carto?
I do prefer their WOW flavors - there are
reviews on the juices and cartos - you can see which ones people like.
Ejuice vapor in general leaves a bit of an aftertaste - a bit of nicotine's bitterness, a bit of flavor, a bit of glycerin's filmy sweetness. Drink fluids. Try some other flavors.
And if you run a carto too dry you could get the taste of singed stuffing (and that will not go away) which is why it's good to add
juice whenever the vapor seems light or a bit dry. You could first try tilting the ecig carto down for 5 seconds or so to distribute the
juice better then if it still seems light or a bit dry add more juice. And you don't have to use their juice.
Find some juices you prefer the aftertaste of. I like their WOWbacco (enough to buy a bottle, and WOWboy is the same but with a bit of mint - both are very cocoa-y) and their WOW Vanilla is ok.