You're the one who has veered the thread in this direction by questioning HyoMin on how she can measure the effort of a given player because in her (and many other people's) opinion poor play stemming from laziness/being unwilling to learn is many times worse than poor play stemming from inexperience/innocent mistakes.
I have suggested that players who's issues stem from inexperience but are willing to lean aren't lazy, they think they're putting in the same effort everyone else is. These players, when confronted with a way to improve, tend to respond favorably or at least give it a try.
Players who are lazy (so, the ones I would say I don't have time or sympathy for) don't respond favorably to cretique because in general they know what they're doing is enough to not die more often than not and that's enough for them.
You (winsock) are literally the one to bring us to this series of questions. You want to know what kind of poor play is deemed unacceptable by many participants in this thread, I've told you. You want to know how such play can ve separared from simple new players still learning, I've told you.
Now on the PUG issue my only comment is that PUGs are for everyone and if that means you get kicked because you're a no AoE BLM or a no DPS healer or a tank who doesn't mitigate... too bad? Just like you guys can tell us to join PF if we want competent party members I challenge you to open PFs for sub-par runs.
Sure, if you actually get a bunch of bottom of the barrel players you likely won't clear anything. That's why queuing in DF is great for poor players. They might get someone like Sebazy as their cohealer for a trial and literally not have to do anything at all. The issue here is that while 'elitists' (lol, I can't believe I'm starting to actually identify with that term) can form groups for likeminded individuals and clear content that way if we did so exclusively there would be no one in the DF pool to carry the very poor players through their MSQ roadblocks like Nidhogg and Shinryu.
This thread is a rant thread and ranting is healthy sometimes. If people want to complain a bit because they feel overextended trying to cover up for bads... Okay? What's the problem?
To answer the direct question at the end of your post if I found myself in that situation I would apologize for giving unclear advice and clarify what I meant. I don't really give that sort of advice, I don't just throw out vague skill names and hope it gets the point across, but this isn't really related to the topic at hand so I digress.