I looked at a few houses today, and the theme seemed to be "control water runoff before it gets under your house". The first was a lovely stucco and stone house in a golfcourse community. The house was situated on a corner lot, where the side yard unfortunately sloped up to the street, which was higher than the foundation. The front yard had a beautiful planting bed ringed with stone. A path of irregular fieldstone wound from the planting bed across the side yard into the back. It looked like decorative landscaping at first. When I walked over the property, I realized that it was a gravel-filled french drain trench topped with the fieldstone pieces to disguise it. The owner had laid the drain trench to try to catch runoff before it got to his house. It might work, it might not, but I wouldn't want to trust it. If the curb is higher than your foundation, the water is going to run downhill, come what may, and you're in its path. He also had a crawlspace exhaust fan and had put pea gravel over the dirt in his whole crawlspace, so I have suspicions that the plan wasn't working.
At the second house we saw something of the same situation - corner lot, side road higher than the yard, sloping side yard. This guy was in the process of installing a french drain around his house and had back-filled and seeded the recently installed trench, which was strewn with straw to protect the grass seed. It was all too obvious that there was a problem he was trying to correct so he could unload his house. Pity the poor buyer who doesn't understand what he's seeing. Let's hope he has a good house inspector.
All this can be eliminated of course if the builder understands how to grade off the lot to control the water flow. I've had two houses that could have had water problems if the builders weren't smart. I live in a hilly area of the country, and elevation changes are par for the course in subdivisions. You don't find much very flat land around here, and if you do, it might be swampy. If you lay out the lot around the house site to allow the water to funnel away from the foundation there's not a problem. Where I live now drainage control is effected by crowning the lot at the house site, letting the elevation roll down slightly toward the property lines away from the foundation, and sculpting a slight dip along each property line to channel the water away from the houses and out to the street. It works wonderfully. There is also a small dip in my back yard that allows the gutter downspout discharge to run away from the house, since they don't go to buried french drains. (It's fine with me, because those drains just silt up and clog anyway, and this method always works. Buried drains may be prettier, but not when you're digging up your lawn to clean them out -- and you always have to, sooner or later.) The street in front of my house goes up a hill, and each lot up the street is slightly higher than the one before it. Everybody's house would be catching the runoff from the house above him on the hill, and the guy at the bottom - i.e., me - would have a terrible mess if this wasn't done right. But in the 60's when these houses were built, the builders were smart about it.
This is just one more example of the axiom - the newer the house, the more careful the buyer has to be. At least in my city. By the late 80's, houses were springing up like mushrooms and had all kinds of problems. The houses built nowadays may be showy, with their granite countertops and such, but if you look at a house that's been there a few years, it will declare its problems. If it's just been there a few months, who knows what you really have?