If you're dealing with a subprime tenant  (FICO < 580), threats for a judgment will probably just end up costing you money and wasted time, so you need to factor that in.

Making threats, even when they aren't acted on and probably never will be is not something I will tolerate for long.

Threats or damaging of property need to be documented even if you can't pin them on someone at this point. 

No matter what, tears, threats whatever.But, I also would tell them I'd give them their full deposit back on move-out day, in cash, if they leave the place empty and clean.  

He kept making threats every time he wanted something.

If the owner has proof that the tenant was notified prior to their lease signing and it doesn't impact their use of the space then I'd disregard their threats. 

He was giving me an implied threat ) then they would sue for damages If I try to remediate the issues without professional mold contractors then the mold spores would spread out and impact the tenants health.

We have a tenant who likes to threaten us, but it is an empty threat.  

They do not guarantee any of this.All a co-signer gives you - is someone else to sue after you evict the tenant.A landlord's only real leverage with the tenant/occupant - is the threat of eviction and of hurting their credit.  

Discuss the smoke that is entering your home and the threat to your pregnant wife's health as a result.