'nefarious motives' is correct and usable in written English.
You can use it when you want to describe someone's malicious or criminal intent. For example, "The hacker was suspected of having nefarious motives in stealing the company's confidential data".
The scientist's job is to "protect the substance of science from those with nefarious motives".
Any hegemonic aspirations and nefarious motives of countries contributing UN troops are more likely to be kept in check.
Its working assumption is that men who get close to high school athletes must have nefarious motives.
As a partisan, I strongly doubt that the current president has such nefarious motives or would stoop to such tactics.
Greve proves to be a formidable and persistent foe, once Brown learns to suspect him and realizes that Greve's unattended Rubens might be a ruse concealing nefarious motives.
Kasdan revealed that it was not the nefarious motives of the studio that caused Costner's excision, just a realisation that his scene didn't work.
Grannis discerned a more nefarious motive, however.
Still, at least one investor shorting the stock felt free to speculate on the financial Web site Seeking Alpha that there was a nefarious motive.
But the producers' lawyers argue a more nefarious motive was at work, suggesting that Mr. Thibodeau was in cahoots with other parties who had an interest in scuttling "Rebecca" on Broadway.
A statement explains the matter, along with implications of a nefarious motive: "Mr. Boxill maintained copies of certain tracks, waited until after Prince's tragic death, and is now attempting to release tracks without the authorization of the Estate and in violation of the agreement and applicable law".
Not everyone has a nefarious motive; not everyone is judging.
