One characteristics of a dirty mouse is that the mouse

One characteristic of a dirty mouse is that the pointer moves erratically. A mouse that is dirty, for example one with a dirty or clogged optical sensor, can cause the pointer to move erratically or not move smoothly across the screen. This can make it difficult for the user to accurately control the pointer and perform tasks on the computer. A dirty mouse can also cause other issues such as not being recognized by the system or causing the pointer to change appearance. Therefore, one of the signs that a mouse may be dirty is if the pointer moves erratically on the screen.