Why are some of my pen lines jagged in my color illustration?

Question

Hi everyone, I'm having an issue with an illustration that I am working on. It's something that I am doing for myself so it's not anything life altering but it's very annoying.
I scanned an ink drawing in illustrator CS3 on a Macbook at a high resolution, I don't remember what that setting was since it was a long while ago, but probably at 300 dpi at least. I then applied a live trace to the drawing to give me more defined line.
I then traced the drawing using the pen tool and added fill colors to them to color my drawing.
I just opened the file to continue working on it only to find that some of the lines are looking mighty jagged at 100% zoom and above. I have never had this problem before. The original black and white line drawing does not have this problem at all.
The problem also seems to be with lines/objects that have both a fill and stroke.
Does anyone have any idea what is going on with this illustration?

Answer 1

John,
Did you read that when I exported the file as a PDF that the jagged lines are still there and that the original scanned artwork that I used does not display jagged lines?
Yes, of course. I read everything you posted.
And also that this has never displayed this was before?
I can't account for what you may or may not have noticed...this way...before.
Vector images should not show jagged lines no matter what.
On the contrary; it's impossible for a monitor to render every angle with perfect smoothness. I stand by my original assertion. Everything on every pixel-based computer display is displayed as pixels. In that respect, vectors and rasters are no different. (The on-screen appearance of) Vectors at certain angles will always exhibit a jagged edge...no matter what. Various angular thresholds render more jagged or less jagged, so it's more and less obvious in different areas.
It's not just the laptop display I'm working on either. The PDF file shows jagged lines on my PC and on my friends workd PC.
Yes, that reinforces my previous statement.
There is nothing in the contents of your screenshots that constitutes malfunction. Your vectors and my vectors and everyone's vectors look that way on-screen. You've demonstrated that it isn't a raster effect or a product of many anchor points, or any mechanical error. I make technical illustrations all day that exhibit similar areas of jaggedness on-screen. It's a simple characteristic of the hardware; nothing more.