It boils down to bad feet.   Last year bought a "frozen" calf that traveled well and found out when I got it home it only had one toe on a hind foot.  Never caused any problems.  When buying short tails, and short eared calves pay really good attention to the feet.  Little shot of dex or bantimine will get them through the ring in good shape and then when they get home its not so great!  It really depends on the sale ring.  Some rings have so much sand, sawdust its hard to get a good look at the feet of the animal.  There are some good bargains but buyer beware have your cow eyes on!  Look at everything!