I am not sure that there is a way to really tell whether they are in tune or not in regards to future predictions. Some readers are amazing at picking up the present and past but get the future wrong often. I think if the reader gets the present and past right I may expect the future prediction to be a bit more reliable, thinking that's a sign of a true connection, but it's never a sure thing. I guess the only way to know for sure is to just allow time to pass and see if it's accurate later. I never read with the same reader repetitively, I always wait to see if their predictions were right before I consider going back.