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Why are polysaccharides not sweet?

Due to the fact that I have taken Biology as an AS subject, I heard my classmate ask this question: what is cotton made up of? When the teacher replied with cellulose, they said: so why isn’t it sweet, if glucose is the basic unit?

I do recall that polysaccharides are not sweet, but the reason behind it, I did not know, until I made some research:

This is the structure of glucose, as you see, it has ‘OH’ groups sticking out. Certain orientations of these ‘OH’ groups react with the tongue receptors, which is the reason why they are sweet.

In contrast, cellulose has glycosidic bonds ‘O-C-O’

You can make out that it is made of many glucose units which have condensed, losing their ‘OH’ groups, which used to be responsible for the sweetness.

Scientists make artificial “zero-calorie” or whatever sugars by adding ‘OH’ groups at a certain orientation to synthetic molecules.

You might have figured out that I was not content with the answer: it has a different structure :)