How does this smell compare to a 'stink'?
sad joke
To your question, with the Volcano or the Herbal Aire I smell nothing until I exhale. I have heard of Volcano leakage on occasion but I have seen Zephyr's leaking on Youtube, so even though you can't see the leak, there might be a minuscule amount of vapor making its way into the air but I wouldn't be worried about it because even if there was visible leak there is still more vapor loss when you exhale a hit as I have said before and I am sure you already know (I just wanted to mention that before the New B's start worrying that they are loosing precious vapor.
I think it comes down to the tear drop shaped bag seal and lining up the zip tie perfectly, that is what was mentioned in the Zephyr thread.