I've rarely used this trick, but it can be helpful, and was on a recent project. The singer/mic combination I wanted for the tunes was a little too sibilant for my liking, and I was afraid the mixing engineer wouldn't have enough tricks in his bag to fix it convincingly. It was the kind of session where the singer sang the songs almost exactly the same every time. So I did a pass of the songs that were the worst offenders with the singer turned 90 degrees away from the mic and back a few inches. So that pass had less of the esses, but they were in the right spots and of course were connected to the proper word. During the comp, I was able to easily cut and paste esses from the 'less sibilant' pass onto the comp track where necessary.