So I have an old crappy house with an old crappy laundry room, and in getting a new washing machine, I can see that there's about a 2 by 3 inch hole in the sheetrock on the bottom left corner of the wall, where I can see the studs/framing. I would like to put in minimal effort, but also prevent rodents, bugs, and airflow through that hole.
Ideally I would cut more wall, square it up, do a california patch and put joint compound all over it. But this is behind a washing machine, and I'll never look at it. Is it a bad idea to get some sort of expanding foam and just squirt it inside the hole to create a seal? I don't know how hard it is to cut out that kind of foam if I wanted to fix this in the future if/when I sell the house.