Good to have that in your lease anyway, most likely tenant will jusy pay the late fee if you threaten to take them to court over it. 

Also threatened me that she would call lawyers etc. 

Ofcourse every month has been painful to collect rent from them because they have threaten us multiple times that they will live rent free until their lease agreement is over. 

Only if the animal was deemed to be dangerous because of a prior history or if it will cause undue financial hardship to the landlord like if your insurance company threaten to drop your coverage or raise it substantially because of a certain dog breed.But even then it’s an uphill climb.

If the prospects were highly motivated, needed to sell and wanted me to come by, and I was hungry and needed to make a deal, there was a time when I would let only life threatening weather hold me back.

I bought the property putting in the offer the following day, after she threatened to sue the buyer if he tried to come up with excuses to turn down buyers she bought over, drag things out, and deal with this other buyer who tried what you're trying.

Took 1 month of time of threaten by management to get them out, and half month to get it clean again.

Then she'll trust you, see how effective you are, and not feel threatened.

Initial talks with FSBOs and off market property owners are less threatening without an agent.

Keep in mind it is currently $400 but can be increased at anytime, meaning it could threaten your cashflow in 6 months or 10 years from now. try the calculation at 450/month to stress test your calculations and see how they work.