If they lose their job, and their income goes down to $0, if the tenant reports a change in circumstances immediately, HUD will cover the rent at 100%.

you may not want to hear this, but in almost all circumstance it is a bad move to rent out a fully paid off house. this is because leaving so much cash in the house reduces your return until almost nothing. 

If you can’t sell it and decide to rent it out instead, that would change your circumstances.

For my taste, I'll take the "better part of the worse area" if that distinction makes sense. 

In rare circumstances, they may bring you something.

@Edward Kozic there is an important distinction that relates to @Tom Gimers point.

@Dave Van Horn :  I like the distinction between working in the business versus working on the business. 

You also need to have more of a margin as Time is against you and it again it is expensive.In Maine and I suspect most of the country, real estates have an obligation to present all offers regardless of your circumstances or the price.

The type largely depends on your individual circumstances. 

They leave when they need to leave by choice or by circumstance.