So, if they tell you there is a hazard where the mower is malfunctioning and don't take action that is where you really create liability. 

You could make a case, if the house malfunctioned, an electrical fire took place for no good reason...the tenant could try and sue BUT you could always put specific language in the lease relieving you of such responsibly, or even make a case that the incident was caused by tenant negligence.

Because the skier signs the waiver and if they get hurt in the normal course of skiing then the judge wont allow a damage claim, but if the ski lift malfunctions then they would probably get some sort of judgement.

Sometimes their meters malfunction or they can tell you if there is a leak somewhere. 

Things like a light fixture that has been removed and not replaced or properly capped off...actual missing flooring...any plumbing leak that would keep the system from holding pressure...a malfunctioning thermostat on the oven...etc.The reason I bring these things up is that if the required repairs - that is the repairs FHA requires to be done before they will underwrite a loan - are greater than $5000, then the property WILL NOT qualify for FHA financing.  

In the event there is a malfunction of an appliance or an appliance is in need of repair, Tenant agrees to notify Landlord in a timely manner and in writing.

We've read of a tenant suing a landlord for providing a lawnmower that somehow malfunctioned and injured the tenant.  

To your note about the tenant complaints, (usually) the only two times I see tenants get involved in those matters are if their quality of life is affected by a building malfunction or if they're what I would call "professional" tenants.

@Rufaro Chirewa all it will take is one system malfunction or a large capex repair for this deal to be an absolute bust, not that it isn't already.

We have a lockbox with a key for backup in case the electrical part malfunctions.