I am not suggesting that one should not buy a used house, I am saying that there are things that you should be aware of when looking at houses. A home inspection by a qualified inspector is highly recommended as a condition in any offer, but there are some areas that you can observe and then decide if you should consider placing an offer or not.
When first walking up to house, look at the final grading. Does it slope towards the house or away? Final grade should always slope away from the house to direct water away from the house.
While observing the grade, pay attention to the foundation. Are there noticeable cracks that water can get into ? This can be a greater issue in northern climates, because when the water freezes it expands, increasing the problem.