I used to love Crocs.  My first pair were the Classics then I got the slippers then the Yukon Sports and told everyone how great they were.  I could not have been so far from the truth.  These shoes keep podiatrists in business.  After 3 years of wearing my Classics nearly every day of the summer and spring I started to feel a growing discomfort in my knees when walking and especially when going down steps and began to suspect the Crocs when I noticed uneven treadwear.  I went to a podiatrist and he said the Crocs due to their spongy sole where not providing support or stabilizing my knees correctly.  He said I was experiencing pronation as a result which explained the uneven tread wear. He recommended Keen shoes instead.  I tried them on and it was immediate relief.  I could literally feel the pressure redistribute in my knees.  It felt like someone opened a pressure valve within my knee joints!  I also learned Crocs act as isolators and cause static electricity buildup which explains now why I regularly would get shocked when stepping out of my van.  Lastly, they are slippery as snot on wet concrete.  Almost went down several times.  They may feel soft on the feet but these things are the devil in disguise.