To cut it out in big /make it black and white, to spell it out / feed it to you with a spoon, the purpose of negative/bad feeling whatever it may be, is realization.

Love the negative.
Feel grateful for Pain.

Otherwise if you had an unnoticed cut, you’d bleed to death.

From whatever negative/bad feeling anything, there is a process, which then ends up in realisation, and often from there happens another process, which ends up in solutions, and most of the time both things lead to some kind of change.
But now if we cut off people at the very beginning, using a word like negative or complain, then how is anyone to come to the changes that are best for them, if you always interrupt the very beginng of that path for them, by placing such a feeling of forbidden on it with those condeming words.
If we mean it well, we weigh our words, and come up with something to say which feels good to that person instead.

This is down among the roots of issues, here one part of where humanity is dangerously disconnected. Dangerously yes, because, it is destructive to our well being, both individually and as a whole. The statistics of how many people are actually on antidepressants (in some of richest and/or seemingly happiest countries) say it out loud.

We are all so different and so similar all at the same time, possessing different natural skills and talents, as well as learned skills and tallents, sometimes natural tallents that are developed further as well.
And there are so damn many of us that we definitely do have all the different people we need for all different anything in any sectors or parts of life.

So if you are a worthy advisor or judge of any kind,

– to put yourself in the authoritarian position with that tone in this whole grand symphony of life and living it in harmony, –
then you know who has the unconditional love to feel with your complainer in constructive ways, unless of course you provide this yourself.  If neither one, then you are merely free to think what you want, but keep it sealed, then you’re not the right one to say a single word.

Think as much of yourself as you have capacity to hold. Whatever you think of yourself, is false if you don’t have something to have it in.
There is no loving whole, no loving sense in pointing out any bad obvious to someone who’s clearly already feeling something bad to begin with, like for example that they are complaining or being negative.
They are not being but feeling something negative.