My experience with YEC advocates is that at some point in their discussions they stop using evidence from Science, and start saying things like:
"It makes no sense to me that one species can turn into another species ..."
"How can randomness (which may not have even been discussed up to then) can lead to the creation of something like Humanity...."
"Evolution is impossible because any change in genetics leads to a loss of information..."
In short: they stop processing evidence and facts, and start fixating on their feelings and their beliefs about facts and evidence.
To answer your question:
"What do you think about the YEC geologists, YEC astronomers, YEC biologists? Do you think they come to their conclusions in good faith, too?"
My answer is a two part answer.
Part 1: Many YEC scientists, without question, think "winning the debate for Jesus" is more important than having the correct scientific answer.
Part 2: The remainder of YEC scientists appear to rely on the limits of human knowledge to find solace for why they do not have the knowledge to refute scientific findings.
This second part merits just a few more words of explanation:
I am prone to say to a YEC at one point or another, that there isn't a single Creationist theory or scenario that explains how air-breathing mammals like whales are never found in the same sedimentary vicinity (in a stack of fossilized rock) as air-breathing reptiles like marine dinosaurs, and what's more, the whales are always in the newer layers of rock.
Rather than accept the inevitable conclusions that such universally consistent observations like these lead to, they simply state that someday he/she/they will have the answer to that riddle.
What would you say about someone who insists that the inner core of the Moon is made of cheese? You can use all the logic and evidence one might think of ... but at the end of the day, that person insists that the cheese will be discovered.
Shall we praise his devotion to his faith?
In the post right above this one, @cwhenderson makes an excellent observation:
Why should the "cheese", or the "Vatican's invisible plains covering the visible mountains of the Moon", be awarded primary Truth in the face of the intelligent minds, granted by God, that provides the insights and facts to conclude otherwise?