> mon and pop situation renting out a spare unit
> small landlord
Those are effectively synonymous to me. The line in the sand that definitively makes you not a small time landlord is if you earn enough from rental income after expenses to make as much as the average job's income.
If you disagree I will need you to define what "small time landlord" means to you then so we can figure out the gap in our understanding.
"Small" is a word indicating that quantitatively relative to other things, it is less, i.e. Very Small < Small < Medium < Large < Very Large.
According to [1] (Doorloop, 2026), Greystar manages 823,581 units as the largest landlord. The 10th largest landlord is WinnCompanies with 120,855 units. These are "very large" to me. If we make a generous curve then a large landlord has 10% of those units, so somewhere in the 10,000 unit range, a medium landlord 10% of that or 1,000 units, a small landlord 10% of that or 100 units, and a very small landlord has the last interval of 1-10 units. Hence, 55 units is somewhere between very small and small.
[1] https://www.doorloop.com/blog/largest-property-management-co...