If your ex offered to take the children overnight & spent the whole time with them round his friend's house, where he gets very drunk on whiskey all night (this is far from a one off) to the point he later sends the children to bed in their clothes & returns them to you the next day, still in those (by this stage pretty grubby)same clothes & pants.
Guess there is little I can do about what he chooses to do with them when he has them, but I don't think he is being very responsible & it makes me a bit cross.