That is shitty man, I fucking hate people who have to go out and deliberately destroy your property because they are jealous or because they have a grudge or what ever .... take it out on the person not their car
I know how I felt when I got hit and run without a package policy (the first night I ever parked my car on the street). I would really recommend a package policy though, $50 deductible costs me about $190 a year for my cavalier.
Hmm maybe the bird poop is why my car hasn't gotten vandalized again ... I wash it they shit on it again right after ... all the time.