The only complaints I've had were, my husband complaining about the smell of "burnt shit" when my coil and wick become excessively gunked from my strawberry & cream; this is why I had to go to an RDA instead of a Kayfun with that juice, because the gunk backwashes off the coil, turns the juice brown, and then apparently smells like burnt fecal matter -- actually, it smells like burnt plastic, which ain't really much better.
And when my stepfather was ill, he said the smell of it was making him nauseous (though I pay close attention to dry-burning and re-wicking, since I became aware of the problem); I've actually experienced a bit of that myself, when *I* was ill; I find the smell rather hard to take, if I'm already not feeling well.
I've not really had any other complaints from anything I've vaped.
Andria