Oils conduct electricity minimally under normal conditions, which makes them useful as insulators. The extent of electrical conductivity depends on the concentration of impurities, so if the oil is very very dirty, yes, it might cause a miss, but it is not likely.
I've run Alfa engines, both 4 and V6, where a plug well was full of oil and the plug did not miss. I suspect at least one of the plug wells in my 91S has oil in it, IIR, and it runs just fine. Bought a set of those seals, but have never changed them. I've never worried about it much, but if it gets to be a bad leak, then I bother to fix it, esp if it is only on the easy front bank. The rear bank? Only if it is really bad.
I'd be more worried about oil getting close to the timing belt more than anything else.
89 Milano (wife's daily driver since 1989, Shankle Sport)
91 164S (my daily driver since 1994)
94 164LS (~Q) (trip Alfa since 2000)
72 Morgan 27 (water time since 1976)
previously owned since 1964:
62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6