Is it unfair to bet with someone when you know that you have special access to relevant information, and that if the person knew you had this access they would be unwilling to bet against you?
This is not merely a common problem it’s one of the core problems of trading, and is practically the plot of Flash Boys, though the author thinks that I should be unable to come to a theory of what your intentions are and use that to inform my bet, because that’s just mean.