For the initial sketch, of course it's going to be messy, but when I do the lineart, I prefer it to be clean. Because I lost my stylus pen, I am only able to use the curve tool from Paint Tool SAI. So, my artworks sometimes come out as stiff because they're so clean and the lines don't have any gaps at all. 
I personally prefer sketchy comics though, as long as they don't appear too lazy or messy. Sketchy can be quite wonderful to stare at. 