I'm asking this because I wrote a novel with 40K words, but somehow I feel it would sell more, or at least be more like a "novel" if I add stuff until it's 50K (I checked on Amazon and most best-sellers are 60K+). Now, the stuff I'm adding isn't entirely unnecessary: they fix some plot holes and add some background to the characters. Still, the novel reads just fine with the 40K.
Is my novel more likely to sell/become popular if it has 50K words? Or it won't make any difference?