It's often hard to know what's a good credential in somebody else's field. Doing this requires knowing how much to trust the PhD from any particular school, how much to trust journals in the field, how much to trust the department hiring process, etc. Remember, frauds and phonies have strong incentives to look respectable, so there's a lot of mimicry in the academy.

One of the major things people typically learn while getting their PhD is who to trust in their particular subfield; this isn't something an outsider can do accurately in two minutes.