It's a Weechester flashback fiesta this week in Season 1, episode 18, "Something Wicked," in which Dean goes to a small town in Wisconsin at John's insistence to finish a literal witch hunt that John abandoned 16 years prior for reasons we don't find out until 3/4ths of the way through the episode.

It's all the angst and guilt you can handle as Dean does the Plot Recap, Sammy gives us the lowdown on the Monster of the Week, and Amanda gives the commentary, a good chunk of which centers on John's terrible parenting. Dean also gives us a really kickass Best Song, and he and Sammy wrap up with Plushies Make Everything Better. 

1.18 "Something Wicked" on SupernaturalWiki
John Winchester on SupernaturalWiki
The infamous Fitchburg sign gaffe