Just use this;
#showtooltip Skillname here (either Cheap Shot, Sap, Ambush or Garotte)
/script UIErrorsFrame:Hide()
/cast Pick Pocket
/stopcasting
/cast Skillname here (name of the spell you chose above)
/script UIErrorsFrame:Clear()
/script UIErrorsFrame:Show()
You need to have auto loot on, this will automatically pick any money and other items from the target and it doesnt show error messages if you cant pickpocket him.
Only works with ''requires stealth'' skills of course
Since humanoids often carry lock boxes that you can pick to level up, this macro is great. You dont have to go search for boxes in the middle of nowhere if you use this.