A Pre Purchase inspection doesn't just tell you if there are termites or other timber pests in a house. It's important to discover and report on conducive conditions and other potential timber pest problems.
One common problem is that houses are left with timber formwork behind when concrete is poured and not removed once the concrete is set. Often this is because the remaning formwork is either inaccesible or difficult to remove.
This formwork creates not only a great food source for termites but also usually generates a great entry point for them to get into other parts of a building.