That's academic theory, not reality. The actual behaviors and background of the tenants is what makes the difference, and people who have higher income tend to

That's academic theory, not reality. The actual behaviors and background of the tenants is what makes the difference, and people who have higher income tend to pay their bills. Also vacancy management is an entirely different problem than quality of tenants and how they treat the property. Turnover of good quality tenants is much better than bad quality tenants who stay trashing the place for years.