Well I have LOTS of experience both in fabricating items with composites as well as repairing them. A LOT of the items on the market today do not have a gel coat. They come out of the mold and get cleared. This doesn't mean they have any UV protection though. There are lots of cheap clears that have little to no UV inhibitors but still make something look shiny.

In my experience the best way to fix a clear coat is to sand as much of the clear coat off as possible and reclear. It usually will NOT make the carbon look brand new because the resin itself actually yellows as well and it's just not possible to sand the yellowed resin off. However, it will make the piece look significantly better.

I have a few items I have redone lately that the customer thought was un-fixable to I'll get some pictures together and do a DIY for those who are wanting to do it themselves.