I am usually pretty nice about running with even the least trained runner as long as they give it an honest effort.  I can always deal with some low quality recovery miles.  Hell, I sometimes lead the "new runners" group run at the running store where I work, and I am barely jogging on those runs. But when a lard-sack shows up to "run", I can't take it.  Even our beginners group is too slow for them.  And they always have something else to blame for their inability to run.  They are either "injured" or "haven't warmed up" or "dehydrated".  But always always always they have nice, new, expensive running gear.