I live in a semi-rural farm town with a lot of small scale farming and orchards. (It's a right to farm town which means people can farm and raise animals if they're over some (low) acreage.) No one generally pays much attention to rusty farm equipment, and yes, the odd broken down car here and there.

But much as I dislike "Your grass is too long and your garden too unkempt" school of HOAs, it's not hard to see why neighbors in a neat suburban development might object to someone moving in with a bunch of junked cars on their lawn.