Lauren Steely emailed to point me at www.earthbookers.net with an example of bad icon design. S/he writes:
You load the kml feed and it displays the locations of hotels in your current view. Opening the Info box, you can see that they’ve tried to indicate the price ranges of the hotels with thin, barely distinguishable colored outlines on the icons. Rather than using four distinct, intuitive colors (red, orange, yellow, green? A color ramp or heat scale?), they’ve elected to go with an inscrutable white, bronze, silver, gold scheme. Not only are these colors difficult to intuitively visualize as a gradation, but the silver is nearly indistinguishable from the white, while the gold and bronze are nearly as difficult to tell apart.
Yes, some kudos is due to earthbookers for incorporating kml into their service but the design could be better just as Lauren points out. I'd add another grumble, there's no instructions so you have no way of knowing that as you zoom in other hotels will appear.
Thanks Lauren, if anyone else wants to send me interesting good or bad examples of Google Earth design then please do.