The problem is that appearances can sometimes be misleading. A previous guest might have opened a bottle, used some of it, or broken the seal without housekeeping immediately realizing it. The next guest may then assume the product is completely fresh when it may not actually be.
The narrator emphasizes that this is not necessarily a major hotel scandal or widespread health danger. Instead, it is a behind-the-scenes example of how hotel efficiency policies can differ from what guests naturally expect. Many travelers simply assume every toiletry has been freshly placed there for them.
