Ah - I'm sure that these terms aren't actually encoded in theory, just things I came up with to understand what little theory I have read better - so destructive labor in my mind is to take something that has value and render it with less value - ie take a well done piece of art and splash color on it, or take a car and remove its tires - both of which could be considered labor, but ultimately make the original object worth less than it was before (wrt to art it could actually make it worth more, but that's only if people somehow feel like the lost worth has any artistic value, which would rarely ever be the case)