I agree with the Dirt Doctor. It is quite easy, to some extent, to see which yards are organic and yards that are not.
The first sign is which ones have the TruGreen trucks coming around.
Oh, it is not a joke. Our neighborhood is fairly young with the oldest parts being approximately 10 years old and their are houses still being built in the newest parts of the subdivision.
Other than those toxic chemical trucks, much of what you say is easy to spot. For example, it is fairly common, in our neighborhood, to see mulch and dirt up against a tree shrub, sometimes up to 2 feet or more!
Plants being planted too low in flower beds so that the house foundation can still be seen. It is good for the house but not the plants.
I am not so sure about the ant thing though. Here along the coast there are ants everywhere and it pretty much cannot be avoided. Our soil is so wet that they find anywhere they can. Generally, the houses here that do not have ants are the ones that have had extremely toxic chemicals put on them.
Other things, like people who rake their leaves, are also a small giveaway. Here, most yards are kept imaculate with grass/leaf catching mowers.