It's been my observation that car keying is an "anger issue" - not necessarily anger at you, but just anger in general. People who key cars are MAD -so they lash out at the closest object to vent their anger ON. Your E may have pissed em off just by BEING there, nothing more. There is no way to stop or prevent these kinds of people from venting themselves down the side of your vehicle...short of a few cautionary things like getting a house with a garage and parking in BFE everywhere else you go, you're pretty much at their mercy.
And you live in a college town, in a college area. I have found that keying is often linked to immaturity - people who haven't yet learned self control or that acting like an azz has consequences. Lots of drinking helps too. Yes, older people DO key cars but usually only the very immature or drunk person over 40 responds to anger by ruining someone elses car - and at that age if it does happen, it's not random - you can figure it's a targeted attack on someone who has really pissed em off.
People who vandalize cars are low-lifes. Somehow they see it as "showing the world" they are in control. If they only knew it makes them look like an out of control 4 year old throwing a temper tantrum - a tantrum with major collateral damage.
Sorry the cameras didn't catch your vandal - scum of the earth can benefit from jail time and financial consequences. Glad you are getting the E fixed. Hang in and think of warm spring days and sunshine. Winter is giving you guys hell this year, I'll agree.