The shelves I'm using are of several varieties.
One had the super cheap particle board and I covered that with a marble look contact paper.
Some of the shelves are just wood planks stained and finished with clear polyurethane.
The others are just standard bookcases.
I've not used painted shelving specifically for fabric storage so I can't tell you anything on that except that it was never a problem when my kids used painted shelves for their stuffed animals, etc.