I have intermediate lines in dark green (cortland), sky blue (cortland), light green (S.A.), amber (orvis), and clear (various brands). They have all been effective for me in salt and freshwater, clear and murky.

A few years ago I was fishing the Fall River in Northern California with a guide. The Fall river is a spring creek and very clear. Dry fly and nymph fishing wasn't working for me so we decided to fish leeches on intermediate lines. I uncased a rod rigged with a sky blue Cortland intermediate line and 7ft leader. The guide said it would scare the fish and wouldn't work. After about the tenth time of hearing me say "oh, that can't possibly be a fish on the end of my line" he told me to shut up. I caught about two dozen fish with that line in crystal clear water.

I had used that guide many times and we were friends and comfortable needling each other. The only reason I use clear lines today is because they are usually what is in the shop. I prefer colored lines because I can see the line and often detect strikes I cant feel. Some of the lines with a clear tip and tinted body have the benefits of both types.