嘴甜心狠办事稳
[zuĭ tián xīn hĕn bàn shì wĕn]
'Sweet Words but Cold-hearted and Steady Action' describes someone who is very skilled at speaking politely and sweetly but actually harbors ulterior motives or has little compassion. However, they are reliable when doing practical work or handling things efficiently. A mixture of charm and cold calculation in character traits.