Well, the Furymint, an herb that resembles real life Spearmint could have some aetheric essence of Halone in it, which neutralizes the corrupting influence of dragon blood. The salt could also taint the blood in some way, or the aethersand acts as a purifier. And, at the very least, the processing, be it heating or distilling, likely destroys whatever component in dragon blood that corrupts people.
Also, minor spoilers:
Rielle from the DRK story line, has dragon blood in her body that she was forcefully fed by her captors at her mother's will so her mother would have a reason to kill her child in a positive light to the papacy. And beyond an above average aptitude for conjury, Rielle shows no signs of corruption.