This is taken from a newspaper article in local Chinese papers recently.
Take note of any unusual markings in front of your house.
It could be a code for these unsavory people.
Translation:
[ + ] or [ - ] means Owner not in the house during day/night
[ Θ ] means Staying alone or Renting
[...] means 3 family members staying
[√ ] means House has been broken in before
[ * ] means Target
[ X ] means Not Target, Not Safe
