I always park next to really new cars, because the chance of a new car owner to carelesly open the door into your car is much less than somone who has got a old banger.
Also I try to avoid next to any cars that have baby seats, kids toys, white van mans etc etc. Sometimes my g/f cannot understand why I do not just park the car is so many empty spaces... I end up driving around finding the perfect spot.
I hate parking dents, they are so annoying
Hope you find out who it is, although I doubt the police can do much really.