As with all things, however, there are exceptions, and one of the major exceptions to the returns game in the publishing industry is in the realm of special markets.
Special markets are retailers that sell a fair number of—but do not specialize in—books (e.g. cooking stores, museum gift shops). Non-returnable (a.k.a. "firm") sales to these customers mean that no matter how poorly the title(s) in question do(es), that customer cannot send the books back to the publisher for credit. Just as with their other merchandise, they keep the product on the shelves until it sells or until they get rid of it at their own expense.
Because the risk is borne by the retailer and not the vendor, sales numbers for special markets are usually smaller and less flexible than they are for most book retailers. They depend to a much higher degree on price point and format, as certain retailers only do well with certain types of books, and most titles will only fit a very few niche special markets. All this to say: there is no universal "special markets book," meaning no title is immune to the spectre of returns.
As you can imagine, most titles sold in to special markets are nonfiction (arts & crafts, cooking, history, science, pop culture, and so on), so your novel is unlikely to be sold on a non-returnable basis in any significant way. However, various author events, shows, conferences, &c will require additional orders, and while these aren't "special markets" in the conventional sense, they very often entail non-returnable sales. There will be some capacities in which your books are safe from returns.
Speaking of returns, tomorrow: the return of... returns!