Today I all day trying to figure how save EPS files (Illustrator 10).
I drew a rose, klick View-> Outline. The lines are good and understandable.
But the problem starts when I saved the file. File-> Save as -> eps
-Version: Illustrator 10
-Format: none
-Transparent;
- Font: leave blank
-Options: note only "Printers default screen"

Close the program, open again. klick View-> Outline and this time all lines are damaged, there is a mess! Can no longer edit gradients. What happened? Is this normal?

Are you using effects not supported in EPS 10?

See this Shutterbuzz article, helped me a lot:
http://buzz.shutterstock.com/bitmapping-101-troubleshooting-eps-files-in-illustrator

Two things you should use to get good and clean stock illustrations. Get a close path script for Illustrator : http://vectips.com/tricks/10-free-and-extremely-useful-illustrator-scripts/ Get the CLOSE ALL PATH SCRIPT. Using thing you will make sure you don't have any unclosed path or stray point.

Also, you can use: http://maps.aridocean.com/scripts_en.php
I LOVE this script. When I create a vector, then save as EPS 10 (or MORE so EPS , then I close the document. I reopen it (EPS 10 or , and then do ExtendedSelect -> Raster Art. This will show which effect has been rasterized (converted to image) because it is not supported in EPS 8 or 10.

Hope this helps! Cheers!

Your problem might only be unclosed path or unsupported effects.

The first thing to understand is how NOT to build your illustrations. You want to avoid the rasterization that can occur upon output to EPS-8 or 10. EPS-8 creates rasters more often than EPS-10 files, but EPS-10 has its own quirks that can make it output as a raster.

When exporting to EPS-8, you will most certainly get bitmapping if you use these effects and techniques:

1. Transparency
2. Opacity Masks
3. Radial Gradient
4. Linear Gradient, sometimes, not always, depends on opacity masks used, or if output Transparency setting is not 100% Vectors on the Raster/Vector Balance (in the EPS Options window, see below)
5. Drop Shadow
6. Gaussian or Radial Blur

When exporting to EPS-10, most of the problems encountered in outputting to EPS-8 are eliminated, except bitmapping will still occur with Drop Shadow and Gaussian or Radial Blur. For those effects, you have to find alternate methods that will produce the same effect (such as Blend Mode to replace Drop Shadow).

When exporting to EPS, always check the Transparency setting in the EPS Options -> Custom Transparency Flattener Options box (see Figure 1). You�ll want this set to 100% Vectors as shown in Figure 1. Check this for EPS-10 as well.