I would say that, unless it’s specifically stated that the vibe is bad, “a vibe” and “vibing” are terms with positive connotations.

So saying “the comments are a vibe” is like saying “I like how these comments make me feel”.

It’s something like the emotional atmosphere or something’s aura.

So a “vibe check” is evaluating how something makes you feel. If it makes you feel good, it passes.