Sue, it all depends on the quality of the photos that GoogleEarth uses.

In most urban areas the images are fairly high resolution and fairly current, from 2010 or 2009.

In rural areas the quality can drop off and the age of the images can range to 5 or 6 years ago, or older.

Because you live in Washington, I looked at the Space Needle in Seattle -- people are obvious but you can't tell much. Cars in nearby parking lots can be sorted by size and model -- SUV or pickup, sedan or compact. The image was taken May 15, 2010.

For comparison, I chose Valentine, Nebraska. The image can't handle zooming in nearly as much as Seattle can. And it's from Feb. 26, 2006. A few miles west of there, the aerial photos are from November 2003.

So to answer your question, if you live in an urban are, you can probably see a 50 pound yellow dog in short green grass -- but it is going to be a yellow blob.