What makes SF apartments smell so bad?

Is there a cure for SF apartment stinkyness? Something about my place just smells old. About half of the apartments I have been to so far are similarly afflicted. Candles aren’t doing it. Cleaning doesn’t make a dent. Making coffee is only a temporary solution. I heard that incense is a good step…but incense is just too gross for me. I am close to buying those ridiculously expensive scented oil stick sets.