I have been a longstanding and loyal customer with Zappos. I always thought very highly of them.
I have never had any problems in the past with shipping, transactions, or products. I recently ordered a pair of shoes by the company EVOLV from Zappos for the standard going price online. When they arrived they were undoubtedly a knock-off of the shoe, as I already had a pair of the exact model and was ordering a second one as mine were getting warn. There are about 20 differences between the two shoes, and overall quality of the pair I received was poor in contrast to my authentic pair.
You can even tell in comparing the online photos of the shoe on the Zappos site (and other sites such as ebay where I found similar knock-offs for sale) to the authentic shoe on the EVOLV site and many other pages. If you know what to look for in the details of the photo/shoe or have had the shoe before, the difference is unmistakable. Interestingly enough, I decided to look for some reviews of others that had ran into this problem. I found a fella on Amazon who had written a review and had the exact same situation with the same model shoe happen to him.
I have since returned the shoes and reordered them from another company and have received an authentic pair. Clearly there is a knock-off of this shoe being created... and sold by SOME venders on Amazon and Ebay. However, Zappos is selling them as well (even the photos of the shoes in the description are the knock-offs).
The scary thing is that if I had never had the pair before, I may not have thought anything of it. This is not to say all of their shoes are counterfit...
however I would most certainly be weary and take caution!