Grouchytown is, apparently, the home of Oscar the Grouch, & the complete opposite of Sesame Street. Grouchytown is 1st shown in Episode 2648 of Sesame Street, in which Oscar & Bob both take a trip there. Luis & Linda warn Bob about going, but he prefers to be open-minded & see how Grouches live.
Grouchytown, like Sesame Street has several different facilities, most of which are opposites of Sesame Street's known facilities. Some examples are, the Break-it-Shop, where Grouches go to get their things broken, instead of fixed, the opposite of the Fix-it Shop on Sesame Street. Another is Worby's Store, the clear opposite of Hooper's Store. The special for that day was a sardine-blueberry sandwich, a pepper-marshmallow steak, & a tomato surprise (which they're out of). Bob doesn't want to eat anything at 1st, but Oscar reminds him that trying new foods is a part of the traveling experience. To everyone's surprise, Bob likes the sardine-blueberry sandwich when he tries it! Oscar reassures a distraught Worby, "He's only a tourist here; he doesn't know any better."
While most residents of Grouchytown are Grouches, apparently, there is 1 nice resident named "Nina the Nice" (a human played by actress Carol Kane). By the end of the tour it quickly dawns on Bob that the nice-human/Grouch ratio there is just the opposite of Sesame Street's.