The room smells of garlic for no reason.

Does the subject want to ask, "Why does the room smell of garlic inexplicably?" There are several reasons:

1 is the smell of radiator flowing through the sewer pipes upstairs or downstairs.

2. Some people eat too much garlic-flavored food in the room, which causes these foods to remain in the air and dissipate in the indoor air with the smell.

3. It's the bathroom.