What does this week's haftarah have to do with the parsha?
It is accepted to say that the connection is in the haftarah's first line. Here the prophet Amos begins a list of the sins Israel commits, and the first is "selling the righteous for silver". This may not be literally be referring to the selling of Yosef, but it certainly brings that sale to mind.
Less well known is that an equally good connection exists in the next verse. Here Amos lists another sin the people committed: "a man and his father would go to [the same] girl, thereby desecrating My holy name". And indeed, in the middle of parshat Vayeshev we see Yehudah hiring a prostitute who turns out to be his son's widow. Thus he sleeps with the same woman his son did, and of course, the whole episode turns into a big "hilul hashem". Amos is presumably talking about a different form of licentiousness, but still, the similarity with what Yehudah did is striking.
We therefore see that the haftarah contains apparent allusions to both of the stories in our parshah (those of Yosef and Yehudah). No wonder it was chosen for this week in particular.