Negative connotations come from religious influences that presupposed sexual desire to be morally suspect (e.g. lust as one of the seven deadly sins).

But even in the Bible (in the Authorised Version) the word isn't always used negatively: the Spirit supposedly 'lusts' against the flesh. (Galatians 5:17).

If there is nothing wrong with sexual desire, then there is nothing wrong with sexual lust: they mean the same thing.