soles of the boots

The soles of the UGG Bailey Button Triplet 1873 Boots Chocolate should have the Genuine Ugg imprint (if you have another genuine pair of Uggs you can compare, if not, there are many images on google and my pictures below). Look closely at the ® which should be in the center of the "3 o'clock" section in between the triangles that surround the Ugg logo. This ® should come out of the sole rather than be imprinted into the boot and should have space above and below the symbol. This symbol should also not wear away after a couple of wears!!
The design of the UGG Bailey Button Triplet 1873 Boots Grey on the sole of the boot should be tidy - The triangles around the logo are usually different sizes or not cut out properly on fake boots. I have noticed that the fake boots have 15 triangles where as both pairs of my genuine boots have 16.

had a pair of Uggs

The imprint on the bottom of the boots should be identical on both boots - There is usually only one curved line on the heel of the sole with one curved and spiked line above it;UGG Bailey Button Triplet 1873 Boots Grey will have 2 or more of these curved lines (see image).
Both imprints on the soles of the boots should be symmetrical. Fake boots will more than likely be off centre and alters slightly from the opposite boot.
The heels of genuine Ugg boots should not wear down easily. I have had a pair of Uggs for over 2 years (very regularly worn) and the soles are only very slightly worn down at the edges.