If the owner envisioned a family coming to stay, perhaps from out of town for a holiday etc, but then instead realized on return that it has been used by a prostitute and a series of men had walked in repeatedly to have sex on the bed one after each other and with each one everyone cleaning themselves up in the bathrooms I can understand how it would feel like a violation. That said, this can always happen and you can't control what someone does once they have your apartment so he's only got himself to blame really, I would not rent out my apartment because I can't deal with knowing someone was in there even taking a simple shower but I understand that about myself and don't care about any income I'm missing out on having it be empty when I'm away.