The biggest lesson I have learned about getting older as a guy in regards to game in this age.

[AmsterdamAssassin]

In this case, a "nasty" girl like that, is really that common to consider for an LTR?

Not if you consider her 'nasty'. If you see her as a problem instead of a challenge, you have no hope in hell to control the dynamic.

THis is just my opinion but I might think that she is nymphomaniac, and is that considered a red flag for an LTR?

Nymphomaniac is bandied around too much to use on women with a high libido. Nymphomania is a mental illness and they can never be satisfied. A highly sexual woman is not compatible to a man with an average or low libido.
So, again, when you consider a woman a nympho for wanting more sex than you're able to give her, you're not a relationship match.

I dislike the whole rating and/or flagging of women or labelling traumatised people as 'broken' because I have relationships with these 'broken' women deplete with multiple 'red flags' for most members here.

I'm quite able to handle the type of women that have ruined many members here, because I don't see them as broken. And I can deal with other people's trauma and drama because I've been traumatised and survived the drama of my misplaced childhood. So what's a 'problem' to most members here is just 'slightly challenging' to me. And I don't mind challenges.
And they, in turn, love me because I don't fall victim to their drama and I can touch what other men cannot touch.