I downloaded a free program so that I can check out these free designs before stitching them out.
I open them in this program, click on the stitch out button, and can literally watch it being stitched out.
If it doesn't look good while stitching out in this program, I don't bother with the design. If it looks okay, I will stitch out a sample for further scrutiny.
I agree with Candace, many free designs are wonderfully digitized, but some are not.
Here is the program I use, click on the Ambassador Set Up icon and follow the directions :D:D:D
http://www.pulsemicro.com/ambassadordownload
It is also useful to watch these being stitched out, you can see the exact spot colors change. I find it very helpful when picking out my colors :D