[Eisenstein]

Critical thought is not about negativity, it is about evaluation. You take a statement and evaluate it based on its merits using an epistemic system which prioritizes consistently, evidence, and logical coherence.

Saying it is disagreeable is like saying that honestly is disagreeable. Sure, it can be, but it is not an inherent feature, and a lot depends on how it is delivered.

[card_zero]

This is the ideal: friendly criticism. But first you have to make friends. If your audience aren't your friends, you can exercise your silver tongue to charm them while still delivering your criticism. If they aren't your friends and you unfortunately don't have a silver tongue, you can be negative, or be quiet, or stick to subjects they won't feel defensive about. You can't have the ideal in practical reality.

[Eisenstein]

If you don't have a silver tongue, say what you mean without denigrating anyone or anything, or just don't comment at all. There is no requirement to be negative for the sake of being negative.