I'm purty fond of dogs, but they got one fault--they're snobs.

They don't like shabby men," Bill repeated for emphasis.
As Whitey thought of this he remembered that the dogs he had known had this failing, if it was a failing.

He also tried to think of some reason for it, so he could prove that Bill was wrong, but he couldn't.

That is, he couldn't think of anything until Bill had gone away and it was too late.

Then it occurred to him that it was only the dogs that belonged to the well-dressed that disliked the poorly dressed.