As the title says , I noticed a few of the doors I clean have a small mark , lookig like a crayon has caught them , didnt pay much attention till i noticed it on several of the doors in my round . Curiosity aroused , I started to wonderr , now Ive realised what the red marks are , but cant think what makes a blue mark on so many doors ? , anyone think of an answer, I wont say what im pretty sure causes the red ones,
Guess any one ?