If you already have an UNhacked version, then dont download the map. As soon as you have to download, its more than likely a cheated map (When comparing the same version). If its a new version, you will just have to open up the jass and check for a cheat.
If its a new version, dont play it, but use the method that matchai said to sort by date. Then once its been checked for cheats you can use it. I would also recommend deleting older versions or moving them to a different folder.
The best way to make sure its not a cheated map is to host it yourself.
Unless you are LOOKING to get a cheated map version, then post it in the request section