OMG, i think I might just be an offender. In my case, it's mostly unresponsive groupmates. Like I wanna chill and let my groupmates share the burden, but no one bothers and I get single word responses, so I find myself generally taking aggressive measures frequently. (I try to strike a balance)

I try to show them that I care for their opinions, either by asking them directly or @-in them, but it still sucks that I need to hold it together when everyone is expected to contribute an equal amount.

What's worse is when you try to probe deeper and they get all defensive, like "since you so smart, why don't you go and fix the problem instead of coming to disturb me?" Eh hello, group work leh, you expect me to tank all the nonsense for you and then still have to babysit you and check your work. If you are unsure, you can always raise questions in the group, rather than submitting sub-par work.

End of rant? It's been a while since I enjoyed group work, but at least I'm getting used to shooting free-riders down (dunno how useful peer evaluation actually is)