Dealing with logical (rather than physical) possibility, the only plausible purpose of thought experiments is conceptual clarification through appeal to intuition;
Intuitions by their very nature may only be used to investigate intuitive concepts; yet
Firstly, there is no guarantee either that intuitive concepts may be made sufficiently precise, nor even if they can be, made sufficiently relevant for the problems of philosophy; and
Secondly, the assertion that intuitive concepts are indeed so relevant begs a mere statistical survey of "folk" intuitions on their content, a procedure widely reviled yet nevertheless the inevitable consequence of the practice of appeals to intuition in general and thought experiments in particular;
Consequently, thought experiments can serve no purpose in philosophical discourse other than to distract from and avoid real philosophical issues, and to block, misdirect from, and otherwise frustrate the precise definition of concepts constructive for clarifying philosophical problems through the red herring of intuition;
I vow never to utilize thought experiments in my philosophy, nor to succumb to the temptation to appeal merely to intuition, when considerations of philosophical work may direct my conceptual clarification in a more constructive direction than that of mere intuitive appeal.