How do you know when you've made a mistake?

James Coleman said every game ever played consists of mistakes. The question is how do you know when you've made a mistake? And what's the difference between a high rated mistake vs a low rated mistake? 

That's the problem. It's hard to interpret mistakes in this game and when you ask a high rated player if he made a mistake and they respond with "yes" i'm like.. how? what kind of a mistake? how are your mistake different than mine?

Usually when my king is in check and it has no squares to move to

i always noticed it after i played the move

That's not good since one can easily get out of checks. now that I cannot recall a time when magnus carlsen was put in check.

That's just vague. Can you articulate an example?

When u feel as if something has been shoved up ur butt, and u realize it only when it is halfway up there

...sorry, but this question can't have better answers...

That's a pretty good answer. 

What if you don't know when something has been shoved up your butt? Not every feels the same. 

It's easy with experience. A well-played chess game has a certain feel to it: your own pieces aren't blocking each other, your pawn structure doesn't have any bad weaknesses, for every attacking move from your opponent there is a good defense, there are several attacking possibilities, units are protecting each other, pieces are coordinated, pieces tend to align such that they invite exchanges, there are good places to move your pieces, you aren't too cramped for space, your king isn't unusually exposed, etc. A poorly-played chess game feels the opposite: it feels like you're always lacking 1-2 moves to catch up, you're constantly on the defensive, your king might be caught in the center with two bishops harassing it and everything around it, your knights and bishops don't have good squares, your bishops are hemmed in with pawns, there are no attacking possibilities, a nasty knight or bishop might be posted where you can't dislodge it, one of your pieces might be tied down permanently for defense, your two rooks might be prevented from aligning due to a posted enemy bishop covering a back rank square, etc. After the game when you go through your moves up to the point where things didn't feel comfortable anymore, you'll find at least one mistake, or equivalently two or more weak moves.

I estimate that one weak move ("?!") is worth half a mistake ("?"), and one mistake is worth half a blunder ("??"). With one weak move you go on the defensive, with one mistake you go seriously on the defensive but can usually draw a pawn down, but with one blunder there is no hope of recovery from that moment on.

You know you made a mistake when the opponent now makes a move or a series of moves that will make you squirm and uncomfortable. Or you realize whatever positive you had has now slipped away.

When my opponent politely reminds me it wasn't my turn to move.

When I sit at the board.

What you just mentioned is the most important thing in the world. this "feeling"

Compare this to touch-typing for example. When you're typing on the keyboard it should feel good right? When I type incorrectly there's always a reason for it and this "bad feeling" can be felt. 

It's pretty straightforward for me because there is a very strong correlation to my clicking the "Submit" button.

When I start cursing at my computer screen, generally that's how I know.

Cursing under my breath for low rated.  Aloud for high rated.

Then ask them to show you the mistake and explain it.

Weak players blunder mates and rooks and etc.

A little bit better you're blundering pawns and such.

Blundering away a whole tempo is bad for titled players.

And there are things like slightly less active pieces, slightly weaker pawn structure, slightly less safe king.  Not only do these add up, but even before the position is technically lost, these mistakes  make the position harder to play and even very strong players will blunder material / mate under lots of pressure.

So when you're reacting emotionally.. a bad feeling

Just making a joke, because of course you don't know you've made a mistake until it's too late... e.g. 5, 10, or more moves later.  And even in analysis it can be difficult to figure out which move started all the trouble.

And the same for bad moves.  Moves which you feel are very bad during the game can end up being the best moves.  Chess is hard like that.

Then the engine tells you something was good, a GM coach tells you it was bad, and the WC tells you both of them are wrong.

It's hard to reconcile what you believe are mistakes since there are no concrete answer or at least that's what it feels.