<human>: Can you provide a brief overview of the text?

So basically, I moved into a new apartment very recently with a friend of mine(also 20 M, he is neat), and, for the most part, I love it. However, the past tenants were disgusting and left the place a mess when they left, and from what I can tell, one of them is returning for this year. 

When I arrived, I walked in to see a room with multiple mattresses and a refrigerator filled with old rotten food, including 6 month old eggs and milk and year old meat, in addition to some perishables bought sometime in August. There was hair in the bathroom drawers and the past residents left a massive amount of their possessions here. With my friend, we already went through and cleaned the refrigerator and the rest of the kitchen area, but I am worried that the person who is returning contributed to that mess. What can I do so this is a non-issue, because I don't want to have to deal with that type of mess this year.
<bot>: Former tenants of my apartment were gross, one is returning. What can I do to make sure it doesn't get too bad?