Part of being great at something includes an ability to abstract out common difficulties, which helps other people to understand (even when you are not that great at explaining).
I'm not aware that I've ever met a genius who was working on completely different principles to other people - everyone reaches the same difficulties and has to find a way to resolve those.
But moderately-good is also not "a sure sign that someone is trying to appear smarter than they are".
> everyone reaches the same difficulties
That is definitely false. I've had difficulties with social skills, the writing process, and knowing how to direct my attention. Some of these are so alien to other people that when I ask questions, it is not uncommon to get responses like:
* Just do the obvious thing.
* This isn't hard.
* What do you think {repetition of my question}?
* You're overthinking things.
* What the fuck is wrong with you?
The folks I've heard get discouraged from maths or science tell similar stories. Part of being good at the skill of explanation is asking questions which help you understand the other person's perspective and what their difficulties are.
A bit strong, and I don't think your examples are necessarily contradicting this. Obviously everyone has their own experience.
Responses such as "You're overthinking things" most often mean:
'I overcame this problem with practice but it happened subconsciously, so I'm not able to express how I did this.'
Part of being great at something includes an ability to abstract out common difficulties, which helps other people to understand (even when you are not that great at explaining).
I'm not aware that I've ever met a genius who was working on completely different principles to other people - everyone reaches the same difficulties and has to find a way to resolve those.