Most grow-ops around here are small 1 maybe 2 room set-ups.
For most of those people they are mortgage helpers.

Lot of landlords get taken, many Municipalities have by-laws that if you don't physically inspect your rental unit every 3 months, if a grow-op is busted or causes a fire they charge the costs to the landlord.
A guy I know didn't do the inspections (they looked like a nice family), a grow-op was busted there.
It cost him
$5,400 for the inspection cost
$15,000 for the mandatory clean-up costs
$5,400 for re-inspection

Plus he must declare the house as a former grow-op when selling which reduces it's value by 20 to 30K

Thankfully there was no fire or it could have easily cost hi another 30 to 40K.

The renter that was busted basically walked away with a slap on the wrist.