When you give someone free art and upon every update they tell you to change something that because of your own personal art style, it’s near impossible to go back and change at that point. 

Also so when the change they want will look horrible, you tell them it’ll look bad, but they whine anyway so you do it. Then when you show it to them they say “you were right it’s bad” 😭

Being told artists don't contribute to society when they ACTUALLY do!

People who make art requests I find too disgusting...and I'm reluctantly giving you an example: Gmaster23 requesting I draw Ash Ketchum's mother from Pokémon shaving her hairy pussy.

Everytime my colored pencils break. DARN YOU PRISMACOLOR WHAT HAPPEN? THESE USED TO BE NICE PENCILS! 
Here, this is a months worth
 

Mine would be when you get a good idea of what to make, and then being completely incapable of making what you had in mind despite how you try to approach it.

i have to be a perfectionist, it has really stop me from improving on my digital art skills

People who get pissed at new artists for “stealing their art style”. They’re learning, you need to leave them the hell alone so they can develop their own style! Of course give them tips and critique/criticism, but don’t be an asshole about it. I also hate people who call themselves art critiques who spread ignorance, saying that “oh it’s the internet they should get used to people saying bad things about their art”. That’s just an excuse for someone to be an asshole. Idk if your criticism is harsh, but don’t just tell them “lol your art sucks” then expect them to just accept that. I’ve been doing art for three years now, so I’m a bit better at responding to this stuff, but you get artists can’t! We need to give them support and help with necessary. Rant over

Le me: *Draws*

Le some random person: Hey, that's pretty cool!

Le me: Thanks

Le some random person: Can you draw me?

Le me:  

When I make the sketch, it looks like it has potential. 

But when I start drawing the line art.....

My pet-peeve would be people who are overprotective over their own art or those who preach what they don't sow.

I've met a number of people within the past 8 years who fit into this category, and when I see these people, I try not to approach them. There's no way I can communicate with them if they are going to be like that. Though, I try to have a moderate judgement when I come in contact with them for the first time.

It's not fair to judge someone without getting to know them first.

realizing i am not really one

I don't know

When I have an amazing image in my head and all that comes out on the screen when I try to draw it is a pile of shit. Sigh...

When you go to erase, and your hand slips causing the paper to crumple up. Let alone if the paper just rips, leaving a massive hole in your drawing.