Sometime... Often... Always, you kinda feel like you are bad and/or going nowhere when it come to art (Be it painting, writing, etc) due to lack of skills or inspiration.
In my case, every time i post something, i'm kinda happy about it, i finished it, sometime i think it's better than the previous one... Then i end up looking up other peoples art on my twitter feed or websites. And then i feel bad.
Basically 100 to 0 in a single web page.
Every time.

But i'm a stubborn motherf*cker (And maybe a bit stupid) so, the day after, i'm back to it. Fully aware of the incoming feeling of failure and incompetence, but still doing it.
I might run into a wall, but i'll try to go through it anyway. And if i fail, i will at least leave a freaking mark.