Indexing in Scopus does not necessarily mean that a journal is not predatory. From the guidelines for being indexed in Scopus:
-The Journal should consist of peer‐reviewed content
-The Journal should be published on a regular basis (have an ISSN number that has been registered with the International ISSN Centre)
-Content should be relevant and readable for an international audience (at minimum have references in Roman script and English language abstracts and article titles)
-The Journal should have a publication ethics and publication malpractice statement
These guidelines could potentially be satisfied by a journal that Beall's list considers predatory. Many pay-to-publish journals advertise "peer review", but it may not even be solicited/may not matter in the "decision" to accept the manuscript.
There also can be information on why the specific journal or publisher is considered predatory on https://scholarlyoa.com. I generally have high confidence in Beall's list--predatory journals do not have a great incentive to turn legitimate.