If we would restrict the conversation at the atty connector, I would be tempted to say that the liquid could indeed be a culprit.
If we were to discuss battery mods where, the body acts as the negative pole, and where the parts do not come into contact with the liquid. Then why do the threads require periodic cleaning? Furthermore, in applications where dissimilar metals are used oxidation is still prevalent without any contact with liquids. e.g the XHaler, the GG, the Screwdriver, to name but a few.
chanderson50 said it best "happens", who really cares how.
The important thing is to do your weekly maintenance and when it comes to the eGo, a quick Q-tip prior to placing the batt on charge as Stubear mentioned, will provide many hors of trouble free, stressless vaping