You are not negligent in allowing your tenant to have a gun on the property, a pool, a bounce house or any other item usual and customarily located on a residential property.Your negligence comes about when, 1. you are aware of the condition and it is within your control, 2. you allow the condition to persist, 3. you failed to take prudent and reasonable courses of action to prevent harm.

Also, if a neighborhood changes for the worse, having too many properties in that area does more harm than good.

@Troy FisherNo harm, no foul...BTW: If you want Rob Ford, I hear he's looking for a new gig ;-)

Done right, a grow op can be done with a small environmental footprint, but as @John D. points out, there are structural limitations to the house that might not allow best practices, in which case a lot of harm can be done.  

@Andrew S. thanks, I guess I am still those that are afraid of them, but really don't know if they do harm.

highly flouridated drinking water, mandatory obamacare/vaccinations, substance dependency, permanent war on 'terror', and media false flags galore all mean we NEED our generous government to survive and remain 'free' meanwhile the balanced 'middle' class are being exterminated from American society altogether.Depend.. or perish!

No harm in this, so long as they are made aware when signing up.I do like to see that you would do local homework, verse some of the other mentors who it seem try and use general info, and apply it to specific markets.

If an occasional scofflaw get by and the tenants don't complain, what is the harm?  

I vote for beefier columns...to add substance to the porch...the porch isn't too large for the house, it is too large for the spindly columns.  

No real harm in it occurring now, from "damages" aspect.