I'm a homebrewer. When I'm working on a new batch of SNPA clone or IPA, I pay pretty close attention to sanitation because five gallons of sweet, unfermented wort is food for all sorts of bugs that could turn my expected masterpiece into two cases of meat marinade.
Same with transferring from pot to primary fermenter, which is topped with bubbling airlock that allows CO2 to escape but nothing to enter. Same with transferring from primary to secondary for clarifying, and the same when bottling. Everything gets disinfected with a 5% bleach solution, rinsed and air dried. Bottles get sanitized in the dishwasher using heat dry.
The only thing that contaminated one of my batches was a yeast culture I obtained from my local brewery!
PG and VG are both alcohols. They make it very difficult for microorganisms other than those who don't require oxygen and sugar to propagate. Those stink to the high heavens and are immediately noticeable. There's no excess O2 in e-liquid and the sanitary effects of the bases, plus the presence of nicotine make it hard for something bad to grow. Even if it did, there's still that red hot coil to get past.
I'm not worried about my e-liquid, but that batch of IPA I'm mashing tonight is gonna be well cared for.