You are right.

As I see it a most grow rooms are added after the house has been built. That is where most of the problems occur. A lot of the problems could be avoided if a grow room was planned for before construction. Proper wiring could be installed and ventilation done while the house is being built.

Sure, it would cost more to build, but all the problems you mention would not happen, so in the longrun it would be less expensive to plan for than to just fix the room up on the fly.

It is a classic case of pay me a little now, or pay me a lot more later. As a landlord it would scare the shit out of me if one of my tenants decide to turn a bedroom (or other space) into a grow room. After they move out, it costs far more to fix their attempt at a grow room then their security deposit will cover.

It is also fundimentaly unfair. The tenant reaps the profit and the free smoke, but the landlord eats the cost of bringing the house back to rentable condition. All the more reason to do your homework and keep your eyes open and to spot check the properties often.