There are a number of signs that a building may be used as a marijuana grow opeartions.
Buyer or tenant unloads unrecognizable equipment and very few household furnishings.
Buyer or tenant unloads copper and or PVC pipe,soil,halogen lamps,large amounts of black plastic aluminium ducting and fans.
Tenant comes and goes at unusual hours but never seem to stay overnight.
Little or no garbage is brought to the curb each week.
Mail is rarely delivered to the house,and the mailbox maybe taped shut.
Windows are always dark and may be secured with metal bars ,blacked out or heavily draped.
A strong odor similar to skunk cabbage (bulk marijuana)comes from the building.
Power meter spins at a very high speed or signs of electrical tampering.
Heavy Condensation on the inside of windows.
Humming sounds of fans or generators.
Condensation or discoloring of the roof.
Unusual amounts of steam comming from vents in the house in cold weather.
Rooftoop with no snow on it when the surrounding houses are covered in snow.
Individuals arriving at the house to put out the garbage ,move toys in the front yard,shovel the snow or cut the lawn and then leave immediately.
People entering and exiting the residence only through the garage keeping the garage door closed.
Excessive security such as guard dogs,keep out signs,high fences ,heavy chains and locks on gates.
http://www.thetorontorealestate.com/