As the owner, what to make of the tenant complaining that the manager is bad

[Ian Moone]

As the landlord (owner), when hearing the tenant complain that the manager is bad, should I be taking that as evidence the manager is indeed bad and should possibly be replaced, or should I take that as evidence the manager is actually good?

On one hand, the statement is the statement.
They are expressing dissatisfaction with the manager, and they feel that way for a reason.

On the other hand, tenant and manager are on opposite sides of a situation, so you'd expect bad tenants to dislike good managers, for doing their job.

For the owner of a property that isn't self-managed, when complaints and issues come up between tenant and the hired manager the task at hand naturally starts with figuring out who's actually the problem in that arrangement. 

[Adam Bartomeo]

You aren't providing enough info. Everyone has an opinion about everything. My opinion is that stocks are bad and real estate is good. Am I right? You need to understand what the tenant's complaint is before you make any decision. You also need to take into account that the PM is the warden and enforces the rules. Most tenants' bad tenants do not like their PM for this reason.