My '92 Accord, which was sitting under a streetlight, was broken into a couple years ago. To this day, I have no idea what they were looking for... No faceplate on my deck in the car, and nothing sitting out that someone would know they'd want. Yet...
They pried the door handle out of the car on the drivers side (the locks are slide lock - according to the mechanic he said you can't break a slide lock by prying out the door handle like you can with some cars - whatever). When that didn't get them in, they went to the passenger's side and pried out that door handle (I guess he didn't learn on the first one that that wouldn't work.).
So still failing to get in that way, he broke the rear triangle window (this is a two-door) and crawled in through that.
He took the CDs (all burned, no originals) out of my visor CD holder and left them on the driver's seat and rummaged through the glovebox.

The only thing he took was a mini-bic lighter that was sitting in the centre console above the gear-shift.
There was a $20 gift cert for a womans clothing store in an envelope on the dash (wasn't touched - but you couldnt' tell what it was without opening the envelope) and there was 15 dollars or so of change in the change drawer beside the steering wheel that wasn't even touched.

So, all told, 11 days car rental (while door handles, rear window chrome trim and bodywork/paint job on both doors was done) and $1200 in parts/labour for that bloody moron to get a bic lighter.

After that, I left my car doors unlocked. There is nothing in my car to steal - so I'd rather them steal the whole damned thing, or just riffle through it and not vandalize my car for nothing.

(And to top it off, it poured like hell all night long soaking the back of the car.)
The guy had to be pretty brave too, because the amount of time he took, underneath a street light, in a relatively busy 'hood... And all that risk for nothing.

I lock my doors now because I no longer have theft on my car, but I also don't live in that 'hood any more - much quieter area and I live in a house as opposed to an apartment. I pity the fool that screws with my car in the driveway...