Wow, this sounds a lot like me! I think its hard to be on "the customer is always right" mode 24/7.
It sounds like the manager might benefit from some training in the area of communication, customer service, stress relief, etc. Grace Hill offers some online classes; which I've learned quite a bit from, but I still have much to learn.
I'm taking a few more seminars this year from
www.Careertrack.com
and
www.findaseminar.com
Also, our local multifamily housing agency sponsors a lot of different training options, including an annual trade show where attendees can choose between dozens of classes based on what their needs are.
Skills, manners, and behaviors can be learned. But the employee has to be willing to accept their weaknesses and want to improve. And most importantly, the employee must abide by not only the local law, but also the owners administrative policies.
If the owner does not have written policies and procedures, they should make some. If the manager does not follow the requirements, there should be consequences. At first, the consequence could be additional training. If the manager does not improve, a probationary period with written expectations should come next. If the manager still does not make the necessary changes, this might not be the best career for them.