Answer:
in several ways:
1. if you leave something like in the middle of the doorway and both you and someone else comes in they could trip over.
2. a child could run into something and seriously hurt themselves (thats if children about)
3. if its also unclean you could end up catching something
4. also thinking about it psychologically it can also make you not look forward to going to work and can cause you to become depressed.