My (and my other neighbors') concern is mostly the type of trees/weeds growing there. The major problem is the ailanthus trees, which are an invasive/non-native, and almost impossible to get rid of once they get established. They will totally take over a yard.
http://www.invasivespeciesinfo.gov/plants/treeheaven.shtml
The other issue is that my neighbors on the other side have been taking care of their FRONT yard FOR FREE for the past two years. It's a rental property, and the owner and tenants can't agree on who should be maintaining the yard.
I feel bad reporting them because I've banged two of their tenants over the past few years, so it's been a reliable source of women for me. But it won't effect the tenants, so I don't really care.
City inspector is coming next week to look at it.