Perhaps what they meant by, "I think this is good", really is them measuring how much pleasure and joy the author feels when looking back on it. They might not be truly defining their work on the basis of their skill or how well it was written but instead they are commenting on how they "feel" about it or how satisfied with it they are. That is the instinct aspect.
When I write, I try to read from the reader's point of view. Meaning I have to feel like I just picked up the work that I have no clue about and I all have to go is the title and maybe the summary. As the writer, I make sure that what ever I have written is presented in such a way that someone who first reads it will comprehend and understand what is happening. You can have a great idea planned out in your mind, and it makes sense to you, but if you don't structure it in a coherent way to readers, it falls flat.
I try to judge my work not only by instinct but sometimes I try to imagine what the readers will feel like when they read my work. It's true that when writing I don't always notice the mistakes I do whether it was grammar, characters, or plot but I change what I can and give it to someone to give me his/her feedback
well..when story comes to me, sometimes i think i know instantly it's good, but to make sure i ask other ppl for opinion because its very important to know what they do/dont like and for me its more fun to see critiques than praises. i dont get what u mean by crock of shit..what sounds? DDD ba dum tssssss
It depends. If it's an area of writing that I am reasonably confident with (such as description), then I feel I'm reasonably qualified to go with what "feels" right (and I suppose this would mimic what you refer to as an instinct). And even then, that's no excuse to not examine those areas just as carefully as every other component of writing.
If someone critiques an area I know I need work on, such as plot, then I will take any help I can get. I know I will need to work harder because it's not something that comes naturally to me.
It benefits a writer to have confidence in one area, and I like to think that those who read widely and spend a lot of their time writing develop something they feel they have an instinct for. It equally benefits a writer to know what isn't coming naturally to them.