Do not ignore the little details...

If he is cruel to his pet, maybe you should abort mission at talking stage.

If the people that are the most closest to him, like his kids, do not believe his promises you shouldn't either.

If he carelessly lose his stuffs; pens, cufflinks especially *phones*, do not hand to him priceless treasures, his hands aren't forged for strong purposes, leave him to remain in the market.