If someone is new to a dungeon or trial, I will do my best to guide them along, explaining the core mechanics and when they show up, it usually works fine. Usually the "new" player is decent and they just need tips for bosses and such.

I know the feel of people using the "I'm new" excuse, we were all new, most of us didn't make the same mistakes. Had a healer who outright couldn't kite the adds for the first boss in Cutters Cry, we told them to simply keep moving as I could keep myself alive with Souleater, but they kept dying, they said they were running, but me and the DPS saw otherwise (they just stopped randomly every time) and then on the second boss, I said they need to esuna off sludge because it deals high damage, they never did and asked why the DPS kept dying, then they quit.

There is a difference between being new and not reading your tooltips/chat log.