I guess I'm not an Atala expert, but didn't those classic Atala racing frames from the '50s, gray/olive paint with fancy chrome lugs, come without tubing labels? I don't know if they were made with pedigreed tubing, but those are not in the same league as "gaspipe" frames. Plus many top shops left off the sticker if they built with a mixed set.

Remnants of a decal is a positive sign. Lack of a decal is a clue, not an indicator by itself. If there's no decal and the frame ends and lugwork are of high quality, it's probably a good frame.