[CluelessMorgan]

Finish off art work that you think looks ugly or chuck it and start again?

Just something that I am wondering since a lot of things I start look ugly.

[Derek]

Depends on why it looks ugly.
There's a phrase at ILM... it's 'Guilding a turd', which essentially implies that a piece of shit, no matter how nicely a coating you put on it, is always gonna be a piece of shit. You just have to know, as soon as you can, why you think it may be such, and if it really is. It takes a lot to have faith in your own work, to have faith in the processs you employ to get a great image born. This is part of that pain.
There is a stage in every piece where, regardless of how good your drawing, refereence, and thought put into it are, you will despair. You have to learn, through experience, when this stage is telling you to stay the course (work through it honestly and diligently and you will end up with a piece to be proud of), and when it is telling you to start over, re-evaluate what you are doing, etc. and to figure out where your problems are.
One truism: when you feel like giving up, stay at it, give it time; if you despise it, put it away for a while, then take it out and see what's up. You will learn and develop perseverence, come to understand when you've just been staring st something for too long, and when you feel the piece is crap when you really just want to do something else or get lazy.