In general I dont really care if someone is good or bad, the only thing I expect is people to atleast try. In groups where we end up hitting a wall I rather try to figure out what we can do to improve instead of playing the blame game.
I dont gain anything by being an ass when someone(s) isnt performing as they should. Using some small icebreaker comments seem to work wonders that and a smile and a good mood. Ofcourse its not foolproof but atleast it keeps me happy.
Im delighted to see the OP being open about her mistake and I think she's right,it doesnt matter who's to blame, its better to work out a sollution then being an ass.