There are two definitions of negging:

The PUA classic: lowering her inflated self esteem so that she will speak to you like a human being.

The Feminist Interpretation: All disapproval or negativity no matter how true.

The modern western woman has no shortage of self esteem pumps: her smartphone which rewards her for posting the most mundane shit, the media which gives women excuses for the most base biological instinct: hypergamy and throngs of betas ready and willing to white knight.

If the modern woman is to be believed any comment that doesn't validate or questions her choices is negging. This kind of philosophy greatly limits what is acceptable to say to a woman.

By the modern definition telling the emperor with no clothes that you can see his wrinkly scrotum and shrived penis is negging.

So yea you should neg, you tell women the truth because its fun to see how they react to reality

The way I interpret Red Pill Philosophy, is that you should act in a manner that makes you happy and is true to yourself.

If you constantly compromise your impulses in an effort to make yourself appeal more to women, then you are living not by your own volition, but by women's rules.

Let that sink in for a bit.

You have one life. Why do women get to decide how you interact with them? So they can give you the privileged of maybe fucking them while they lay there like a cold motionless starfish.

Fuck That Shit

You knows whats better that sticking your dick into a loose bucket slut vagina?

Emotional Manipulation

There is a certain pride you get from knowing that you can dictate a person's reality just by speaking to them. You can undermine their beliefs, sense of self, values and national identity with words. That my friends is empowering. Empowering in the true sense of the word, not feminist empowering i.e showing cleavage in the workplace for attention.

I once introduced a girl to nihilism. Her belief in a higher power took a large hit. She unfriended me on Facebook and told all her friends that he makes me feel and believe things that no one should ever feel or believe. Just because I said there is no such thing as fate, the world is inherently unpredictable anyone can die at any moment and that all morality is invented by man to control man. Because I said some words her world collapsed. That my friends is a mindfuck, and a colossal lol.

If you are truly Alpha then you decide your reality and the reality of others. A Beta lives the reality of others.

TLDR: You should say whatever you want. Betas ask for permission and are concerned with feelings.