Dirty neck rings around shirt or blouse collars or anyother stains such these, can be removed by putting shampoo on them. Rub the shampoo in like you were washing your hair. Shampoo is specifically made to remove body oils. you can buy a cheap bottle of shampoo for such purpose.

thanks for the post, and it can be used when traveling too.

Hair spray will remove magic-marker ink from surfaces too.