All writers have a little voice in the backs of their heads that tells them their writing sucks.
If you've never heard that voice, then you aren't human.
Most of the advice on managing that voice follows the logic of books like The Power of Now, suggesting you calmly and dispassionately observe the voice, thereby minimizing its hold over you.
This is wonderful advice--and sometimes it even works. But if you'll bear with me for a brief tangent, I'd like to offer an alternative viewpoint.
Here's the thing. We all write things that suck. It's a fact. However, when we start writing a new piece, it's rarely clear whether that piece will suck or not. Some of the things we write will start out with great promise, but then end up sucking. Other things we write seem horribly stupid at first, but then we stumble onto some important insight and suddenly the piece transcends suckdom and becomes something with true potential.
The thing is, most of the time you won't know which of these two outcomes will happen. And yet that voice in your head is chattering away, totally convinced your writing sucks, and desperately trying to convince you of the same.
And that's the insight.
Why is it an insight? Because that little voice in your head, when it tells you your writing sucks, doesn't actually know. It can't know! Neither you nor that goddamn voice really knows what's coming. What you're writing might suck, but it might not. And hey, even if it does suck, you can still work on it until it doesn't.
That's why there's no point in judging your writing projects until they're within shouting distance of being finished. Just see how they turn out. Have faith, work at it, and let the process surprise you. You'll prove that damn voice wrong.