Sending back known lame pattern packs is not unethical. It takes alot of rationalization to convince yourself switching out minis is ok.
It reminds me of the time my son had to do a report on the ring-tailed lemur. We went to Barnes & Noble, which is 20 miles away, to see if they had any books, and the only one was an encyclopedia style book that was $80 and had just one partial page about the lemur. I whipped out my phone to take a photo of the page, and my wife says, "You can't do that, we'll buy it, take it home, copy it, and return it tomorrow." So I said, "how is that better? I'm saving us the one hour round trip and a couple of gallons of gas."