There's different kinds of novelty shops. Some specialize in dreck, like the various Spencer's Gifts stores at almost any American mall, where there's a lot of potty humor and blacklight posters. The sort of place you'd go at Christmas time to find a tie with a naked lady on it for your weird uncle. The fact that these stores survive is a testimony to the hunger for amusing crap that inhabits the human heart.
Others aspire to a higher quality of kitsch, like Ruby Montana or Archie McPhee's, where you find less stuff concerned with genitalia and more things along the lines of glow in the dark religious supplies or lunchboxes with Hindu gods on them. Here, much of the novelty derives from a familiar object given some different treatment, or an object familiar in retrospect made strange by putting it in the surroundings dictated by today. This is the land of Elvis paraphernalia, for one. Too much wandering in such stores may lead to madness, or to an overabundance of plastic dinosaurs in one's domicile.