Something that caught my attention is that you say you are using soap. Soap, by its nature, sticks to things unless it is rinsed off very, very well. Are you sure that you haven't accidentally left a little bit of soap on some parts over time? I would stick to alcohol cleaning if I were you... or be sure that you can really rinse the soap of very, very well with extremely hot water.

The residue from vaping shouldn't smell bad. I mean, I don't think it smells "good"... but it shouldn't be a terribly offensive odor.