There is an issue in SL at the moment where the difference in lighting with different combinations of basic and atmospheric lighting makes tinting your body attachments difficult if not downright impossible. I have logged a Jira for this issue here.
Anyway, the problem is thus:
When your Atmospheric shaders are turned off, or your Basic shaders are turned off, the light that falls on your avatar from the sun and local lights is very different to the light that falls on prim objects. Since weighted (rigged) mesh is just another type of prim object, this means that the feet will never ever match the leg they are attached to, no matter how much you adjust the ankle blender and foot tint. As soon as you turn around, or stand next to a local light, you will see a very ugly join.
To other people with the shaders enabled, your feet will look just fine as long as your ankle blender and foot tint and texures are the same.
To workaround this issue:
1. go to Me, Preferences, Graphics
2. Check Basic and Atmospheric shaders.
If you experience loss of framerate with these shaders on, ensure your water reflections are turned to minimal, and drop your draw distance down a little.
If either of these options are greyed out/not available, then there is a good chance that your video card doesn’t support these shaders and you may need to look into getting an upgrade, as this is the least of the problems an unsuitable video card can cause.
If you enable these shaders but your feet don’t improve, you may need to look into updating your video card drivers. The major video card suppliers update their driver sets on a very regular basis to keep up with changes in technology.
To find out about your computer, go to Help, About Second Life. In here is listed your system spec, and you will find information about your operating system and version, video card vendor and video card type. You will need this informaton to find an updated driver.
From here, provided you have an ATI/AMD or Nvidia card, you can go to the manufacturers website and search for the most recent driver.