Or rental demand could be poor leading to higher than norm vacancies.

Difficulty filling vacancies?

How are the sellers being protected, in the event things change, vacancies increase and mortgages can't be paid? 

I have two vacancies in two different markets and it has been extremely slow despite the positive feedback and price. 

This would be in class b, class c will have higher maintenance/cap ex on average. you have $0 for vacancy.

If you don't you will lose a lot of money with evictions, lost payments, and vacancy.

(Be sure to factor in vacancy, PM fees, maintenance, etc in addition to PITI)•Do you have additional reserves to cover unexpected expenses like long than expected vacancies, high turnover costs, or major repairs (e.g., HVAC or roof replacements)?

In reality, most older homes will cost you considerably more in maintenance, capital expense, and vacancy (people just generally like to live in and rent newer homes).

It did cost more money than expected due to vacancy that I did not account for.

A couple years later, repairs, vacancy and turnover costs and you've actually lost money every month and you've decided to sell and buy in a more desirable area, but the property hasn't appreaciated, you have to fix it up to sell and incur transactional costs and you lose even more money.