Generally you buy (or sell) a house "as is" so let the buyer beware.
The courts have decided that a strict application of this doctrine would be oppressive and unfair to purchasers so the law provides relief in certain circumstances. The courts have made a distinction between a patent defect and a latent defect. Patent defects are defects that are discoverable on a superficial inspection of the property by an ordinary purchaser. A vendor does not have a duty to draw the purchaser's attention to patent defects. An example of this might be a large crack in the side of the house.
If the purchaser fails to observe patent defects when inspecting the property he cannot later complain about them. The doctrine of caveat emptor applies.
Latent defects are defects which an ordinary purchaser would not be expected to discover in a routine inspection of the property. An example of this might be termite infestation.
In a situation where a latent defect is unknown to either the vendor or the purchaser but is discovered after the signing of the agreement of purchase and sale, the courts have generally decided in favour of the vendor and the purchaser must take the property as is without compensation for damage occurring as a result of the defect. This is a common scenario.
If the vendor knows of latent defects but does not disclose them to purchaser, the doctrine of caveat emptor may apply but if the defects are actively concealed by the vendor the doctrine of caveat emptor does not apply. An example of this might be if the vendor patched the crack in the wall in order to hide a structural deficiency. In this case the purchaser can ask for rescission of the contract and\or compensation for damages.