Probably not a recommendation in the first place but have you ever asked for a letter of recommendation and instead of getting one that is positive you get one that is negative or iffy?
International Level: Politics 101 / Political Participation: 5 0.5%
"Well, he showed up on time some days and did the bare minimum to keep me from firing him outright. If that's the level of dedication you want, he's perfect!"
Humor aside, I can't say I have received a negative recommendation letter personally. Then again I don't tend to ask for such in the first place.