Pinchfield has been accused of cheating and involved in lawsuits before, so it can be predicted that he might cheat Napoleon.
Frederick of Pinchfield is described as “a tough, shrewd man, perpetually involved in lawsuits and with a name for driving hard bargains” (ch 4). If he has been sued before, he has probably cheated someone before.
At issue is “a pile of timber which had been stacked there ten years earlier when a beech spinney was cleared” (ch 7). Whymper had advised Napoleon to sell it, and both of the farmers wanted to buy it. The animals decided that Snowball was in league with first one farmer and then the other.
Of the two, Frederick was the more anxious to get hold of it, but he would not offer a reasonable price. (ch 8)
The animals distrusted Pilkington, but “feared and hated” Frederick. Yet they did business with Frederick, and Frederick paid with fake bank notes. The animals did not trust him, and he did trick them. Napoleon is angry, and pronounces a death sentence on Frederick.