[Steuard]

I am a native speaker, and "promiscuous" is definitely a negative, pejorative term. (Dictionary definitions are good at capturing the denotation of a word, but are sometimes less good at explaining its connotations. If your dictionary lists additional/alternate definitions of this one that apply in non-sexual contexts, look at those to see if they appear to carry positive or negative implications.)

[jessaustin]

It's clear what is being discussed here, because "promiscuity" has a simple understandable meaning. In certain contexts the word has a negative connotation, but only because those contexts morally disapprove of the condition the word describes. One would have hoped that "native speakers" could have offered a different, more suitable word to employ in this discussion, rather than just ruling the discussion out of bounds because they don't like this particular word.

[fxbl0i]

Promiscuous is a pejorative term because the act itself is socially seen as negative. There is no way of describing promiscuous behaviour positively, so the choice of word is irrelevant.