I used to work as an instructional assistant at a community college. One evening I was making my rounds in the lab and noticed grey muddy footprints all over the shop floor so I followed them around though the library and into the shop where I met up with the student who made the mess. He was speaking with another student, so I went and got a mop and bucket and brought it to him and said "Here you go". He appologized and went off to mop up the muddy mess. The student he was speaking to informed me that the mud on his shoes was from the ash of his house as it had burned down in the forest fires that were raging at that time. Needless to say I felt about 2" tall at that point. NEVER assume anything.