You will never be told about the variety of people that you will meet during your career as a property preservation contractor.
Work on enough properties and you will eventually encounter vagrants. Most of the drunks will be asleep in the back of the house and are not necessarily dangerous but caution is recommended. Druggies are another matter entirely. Leave and call the cops.
Of course vacant properties are used for other activities also. You may eventually find properties that are used for free condom parties – the evidence is everywhere, and lots of properties serve as the temporary headquarters for local social groups. Here is a link to a story about vagrants in vacant properties, broadcast by WSOC TV in Charlotte. Just so you have an idea of how wide spread the problem with vagrants in vacant properties is, go here and type in “vagrants in vacant houses.” You will be shown hundreds of pictures related to news stories about vagrants and vacant properties.
Many vacant properties, depending on their location, also serve as the local construction supply warehouse. These properties are used to supply light fixtures, electrical components, water heaters, air conditioning units, cabinetry and a variety of other materials. Depending on time of day and weather conditions, you may encounter shoppers.