Anyone who thinks that vaping leaves no trace needs to get in my nephew's car. He loves those fruity scented high VG vapes, and you can smell it outside the car with the windows closed...
Oh, and it's not water vapor. It's propylene glycol and vegetable glycerine being burned, and the VG definitely leaves an oily residue that can't be easily removed from drapes and room linens.
That's why it's banned in staterooms.