I recently ordered the tinted (SES) OEM tail lights for my '10 focus. As Ford has done with many tail lights on recent models, the lights dont have a finished edge. It looks very cheap and doesnt blend well with the vehicle.
Here is what it looks like from factory
As you can see the edge of either the tinted or chrome light ends up looking white. A much better finish would be either black or the color of your vehicle.
To do this you simply remove the light and paint the inside of that edge. Dont worry, it is sealed off from the rest of you light, so you dont have to be an artist. YOU DO NOT HAVE TO DISASSEMBLE THE LIGHT HOUSING. I used black automotive spray paint. The color is up to you just be sure to use an automive paint. With a small nozzle you can carefully spray the paint on the edge or through the crack to fill in the edge. Another method is to fill a syringe (without the needle of course) with the paint and spread it onto the edge. A small delicate paint brush from a craft store can also help.
After the edge is painted, I use a good RV/automotive sealant to seal off this newly painted edge from the elements. Applied by hand worked best for me.
Ive done this to both my Focus and my F150. It can be done on the tinted or chrome lights.
Here is another thread from an F150 forum that details the process and has a ton of before/after pics showing different colors used.