For contemporary poets, it's likely you'll need to look outside scholarly criticism and book reviews from established print publications (see Reviews of Poetry page at left).
Every source should be evaluated individually. Use these criteria. When in doubt, ask a librarian.
Authority:
Who is the author and what is her expertise? Does she have the credentials to be writing about the topic?
Do a web search on her name: What else has she written, where does she work/ with what organizations is she affiliated?
Do you not see an author? Move on! How else can you vouch for their expertise?
Publication:
Use the About page to understand the purpose and mission of the site. Investigate the editors' reputations in the same way you would an authors'.
Citations / Evidence:
Where do the authors get their evidence? Do you see citations and references to scholarship and research?
Are you seeing a lot of opinions? That's ok as long as that is the author's job (to review, critique). Just investigate their reputation and the reputation of the publication(s) they are employed by.