The reason why Japanese real estate agents try to unload those properties on gullible foreigners is because Japanese people don't want them. Some of those properties are jiko bukken, which is a property where someone died or where some terrible crime was committed. There's a cultural stigma against these properties, so nobody wants to live there. If someone actually does buy and move into the property, the neighbors shun them. The other "cheap" properties that don't have this stigma are often in really bad disrepair. That's not necessarily terrible--there are plenty of gutjobs in the West--but they're not actually cheap, plus you have to deal with the local bureaucracy making sure you repair it the way they want.