Thanks for the replies,
What I have appears to be the same as the poster you mentioned Ken, the spots I was trying to smooth out were along the edge of the reinforcement tape I put on the keel line at the stern. At the bow I used a diagonal cut piece of 6 oz cloth and it looked fine. At the stern, however, I used a length of 3" wide tape on top of the standard layup of 6oz cloth and I had some runs and a slight lift of the cloth at the corners that I thought needed cleaning up prior to applying more epoxy that I would just have to sand off anyway. I scraped the runs and sanded the edges of the cloth slightly, it was the cloth edges that discolored.

I should probably mention that I am using system3 epoxy.

When feathering in a reinforcement layer I should not sand into the actual cloth but only sand the surrounding layer of epoxy??

These were questions I was not able to find answers to after hours of searching through previous posts and many construction websites.

Thanks for your advice.