There are several tenets of cozy mysteries and one is that they are “clean.” No profanity, no violence, and no sex.
I can’t tell you how many times I’ve seen 1-star reviews on Amazon with the main complaint being the language. I’ve always tried to limit my use of profanity in my books, even in suspense novels or thrillers. I simply believe that dropping F-bombs all over the place is lazy writing. I also believe that if used sparingly, profanity has more of an impact when it is used. But none of that is a concern with cozies. Only the mildest of expletives are used, if at all.
Graphic violence is also a no-no in cozies. Although there may be a murder, it usually happens “off screen” and is not explained in detail. Gory descriptions aren’t included. Details of the murder are not explicit or used as clues. The killer is also typically a member of the community, able to blend in or “hide in plain sight.” Psychopaths and serial killers may be primary characters in crime novels or thrillers or horror novels, but not in cozy mysteries.
And when it comes to sex, the bedroom door remains firmly closed. Sex, even among married couples or consenting adults, is only implied. In many cozies, sexual activities are avoided altogether. Whereas so many movies today push the limit of the R rating, cozies are rated a solid PG. Your young daughter and your grandmother both should be able to read a cozy mystery without feeling embarrassed or uncomfortable.
With cozies, the emphasis is on problem solving, quirky characters in an appealing setting, and often hobbies or pets rather than sex and violence and language that would make a sailor blush.