What I recommend is that you never reveal yourself to another counter. I won't even reveal myself if the pit boss is hawking my game too closely. Instead, switch to basic strategy, maybe even make a basic strategy error or two on a min bet, observe them discretely, determine if they are a counter (you will get some warning signs right off, maybe an unusual basic strategy play like hitting A7 v T or 12 v 3, or a correct index play), and then never play at the same table with them again for the rest of my life.