Does this sweatshirt fit true to size?

No. It is listed as fitting small, so treat it as a snug small rather than a standard small. Check the measurements against a sweatshirt you already own.

Is it really a 1990s Gildan?

It is described as a vintage 1990s Gildan blank in very good condition. Gildan has made plain crewnecks for decades, so the tag and stitching are what confirm the era.

A cotton blend, listed as 50% cotton. The rest is likely polyester, which is typical of Gildan blanks and helps the sweatshirt hold its shape.

Is it good for layering?

Yes. A plain black crewneck is one of the easiest layers under a jacket or over a tee. The small fit means it sits close to the body.

How does it compare with a new Gildan sweatshirt?

A new one gives you a known size and a fresh, stiffer hand. This one offers the softer, worn-in feel of older cotton, but you accept the small fit and single-unit availability.