Do your due diligence to ensure the specific terms of the offer make sense, that the buyer has proof of financing or proof of funds, and that nothing is going to prevent the closing from going through as expected.

I don't think you can prevent people from owning firearms and keeping them at your property. 

I googled this and found:If a tenant fails to pay rent or violates a term in the rental agreement, an automatic stay will prevent the landlord from giving the tenant a termination notice or from beginning the eviction process if the tenant has already filed for bankruptcy.

HOA prevent me from painting my house all black or all red.

A final thought; it's kind a of a shame the tenant decided to implement her own little passive-income strategy here because now she will likely have an eviction attached to her and she will be paying my lawyer's fees and costs of restoring any damage to the property and related losses.

I have also implemented a strategy to make the deal more enticing to potential tenants.

Consequences of not understanding or implementing proper accommodations for owners of certain types of 'animals" proves to be VERY steep--read about a Landlord who lost $1Million lawsuit:https://denver.cbslocal.com/2019/06/05/meeker-emotional-support-animals-lawsuit/

Sometimes your cash flow won't be able to support the capex needed to make the property run efficiently or help you implement your business plan successfully. 

No response (until after it was done and they put it upIn a day) Having a job I have to be at, it seems anything short of laying down on the property like Tieneman Square could have prevented them building it. 

It’s not really a “lien” but a type of “interest”.This a strategy, and sometimes an extortion type game, where they try to prevent you from selling to someone else.....it’s Proper use is to protect them when they Do have a valid contract on the property.Clarification needed: did You refuse to close the sale or did the buyer fail to close on time?