Several years ago, I started looking at 640 acre parcels, wanting one that I could use to escape the pressures of civilization. I eventually found one that I liked well enough to buy, although I still haven't scraped together the cash to put in my airstrip and mansion.
The search was quite educational. I learned:
If an eBay land seller is honest, then he's probably incompetent. They will copy/paste their ad numerous times for different pieces of ground, and in the process forget to update the GPS coordinates, the county parcel number, or the range/township/section numbers, and when you try to find the parcel, it ends up being in a different county than where they claimed.
One common eBay trick is to show pictures of the "general area". Or, they will claim "views of the XYZ Mountains", and only show pictures of the XYZ Mountains. This is because they don't want to show the salt flat that they are selling.
Google Earth is a fantastic resource for checking out land. However, for remote parcels of land there is often no official street address. The seller will usually post the range, township, and section number, which Google Earth doesn't understand. You can go to earthpoint.us website and click on "Township and Range / Search by Description" and it will either give you the GPS coordinates, or you have the option of letting it launch Google Earth for you and it will draw a square around the section.
Here are a couple of more Google Earth tips:
Use the perspective view to look east and west from the property to give you an idea of what your sunrises and sunsets will look like.
Click "View / Sun", and it will draw the sun's shadows and give a time slider. Zoom in and out on the time slider, and you can use it to find out when the sun hits the land at sunrise, and when the sun sets at different times of the year. This is invaluable if the land is in a canyon or next to a mountain, especially if you want to use solar power.
If you're looking at land in eastern Oregon or northern Nevada, look for sand dunes near the property. Sand dunes don't form unless the area has extremely high wind!
Look at the elevations of any nearby residences you spot on Google Earth. If they drilled a well, and if they're at the same elevation or higher, you should also be able to drill a well. If you're a thousand or more feet higher on a rock, you might be out of luck.
Finally, it's quite helpful to look at the historical temperature, precipitation, and snowfall totals at the Western Regional Climate Center.
http://www.wrcc.dri.edu/summary/Climsmor.html