I know that everyone's feet are different and that what works for one isn't necessarily right for another. But to only give a pair of Kenetreks a 3 mile test doesn't tell you much. Their website says 50 miles for full break in. In my case it was pretty much the truth. I was ready to give up as well, but stuck with it and they are now my favorite boot ever.
Your milage may vary of course, and good luck with the sale. Someone is going to get a great deal on a great boot.
If you change your mind and want to give them another try you can speed the process a bit by putting them on and standing in a deep bucket of water until thoroughly soaked, then wear them around while working in the yard for a full day.
Either way, good luck!