Keep Stripping
No ... we're not talking about removing your clothes. Having spent literally thousands of hours on the flats, I have learned that often, just when I'm about to give up and cast again to another fish, a fish eats my fly right next to the boat. Why this is so is a subject of some debate, but the fact remains that a fish we see and cast to at 80 or 90 feet magically seems to disappear, and then right at the boat he eats.
The moral of this story is quite simple, do not give up on a cast, especially in cloudy water or under any circumstances where visibility is limited. Often, the bottom of the flats and the fish are the same color making it difficult, and sometimes impossible to tell apart. Under these conditions keep stripping until you run out of fly line (you do not want to bring the last of the fly line inside your rod tip) and you might be rewarded. One of the most frequent things your guide will say to you during a day on the flats will probably be "KEEP STRIPPING!!!"