Guests having sex in your home

What are your opinions on house guests having sex in your guest bedroom. What is the proper etiquette? Some people don't like for others to have sex in their home. My opinion is if I invite or allow a couple to stay in my home, I'm sure their going to have sex and don't mind, I just change the sheets after they leave. I mean it's no surprise, especially if they're around my age (early 20s.)