I own and let a flat in a poorer part of the city I live in. I'm very lucky that my flat is rented to an accounts assistant and a newly qualified pharmacist. The downstairs flat is let to a less-salubrious tenant.
My poor (OCD) accounts assistant was REALLY and understandably distressed when the sh**y scruffy downstairs tenants allowed rubbish to pile up in their yard, resulting in a rat infestation. He videoed them and sent me the video.
Fortunately, said tenant is a very sharp young man and tracked down the owner of the downstairs flat online and sent me his email address. I then forwarded the ratty video.
As my tenant said, the video was like something out of National Geographic.