I do it all the time, throughout the writing process. The flip side is I also get moments when I'm thrilled by my cunningness at plotting, my abilities to create new words (like cunningness), my nifty bits of description. I ricochet from despair to elation and back again, like one of those pendulum games that used to be a fixture of every executive desk in the 1970s, eventually settling for: It'll have to do.
What I can do without is outside comment that it's rubbish. It's a strange thing - I don't mind reading between the lines when my writing friends tread gingerly round the rubbish writing question - 'No, no, it's fine, I just wasn't sure you'd got the right approach...' Then, I'm quite happy to have a giggle at my own idiocy and get re-writing.
But outsider comment is lethal, especially when that person might have a stake in it like an agent or an editor. I once sent my agent a synopsis for a novel I was 20,000 words into. She didn't like it. I stopped writing immediately and started something new, not because I didn't like what I'd already written but because I'd lost confidence in it. My editor occasionally volunteers to have at look at work-in-progress, but I refuse - I know my limitations and one negative from her would scupper the whole thing.
So, how to cope if your outsider comments are coming from real outsiders, by which I mean people who you are writing to on spec, like agents and publishers?
1. Only send out work that you are as confident in as it is humanly possible to be.
2. Get a friend (or friends, even better) to vet your submission before you send out in case there's some major league problem you haven't noticed. (I recently looked at one where they'd forgotten to put their contact details anywhere in the package. Strange but true.)
3. Send out multiple submissions so one negative response doesn't derail you.
4. Send out multiple submissions so one positive response doesn't derail you.
5. Put all comments you receive, both negative and positive, to one side for at least 48 hours until you've calmed down and can attempt to be rational about them.
6. Ask a friend to read any comments. Their take may be quite different from yours - I once consoled a tearful recipient of what was supposed to be the most soul destroying letter in the world. It was full of nice, albeit slightly guarded, comments, and a request for more. The teary writer had only registered the qualifiers and hadn't taken in the request for more.
7. Build a support network. It could be writing friends, it could be your mum, it could be your partner. It could be people on Twitter, Facebook, it could be anyone. But a support team is vital to keep you going in those dark moments when you know you're rubbish, your writing is rubbish, there's no point to carrying on.
8. Use negative feedback as a spur. It's fine to wallow in misery for a short while after receiving a rejection, but far more useful is to grab your 'I'll show them,' attitude and use the energy to get writing again.
9. No one has to write. It's not compulsory. I make my living from writing, but there are other jobs I could do. Tell yourself you can walk away from writing - but if a spark flares up inside you that you don't want to walk away, then use that spark to motivate yourself again.
10. I look back at stuff I've written and some of it IS rubbish. And some of it is really quite good. But it rarely coincides with what I thought was rubbish or good at the time. You are not always your best judge, but time and experience can help to make you so.
I think all of us writers have to accept that we can be both rubbish and brilliant at the same time and just because someone gives you a negative opinion today, it doesn't mean there won't be a positive one tomorrow. Positive, negative, rejection, acceptance, brilliant or rubbish. These are words we have to live with if we want to be writers, two sides of the same coins.