This is something that has always confused me. I understand you're supposed to ask permission before you do anything for someone, whether it be healing or whatever. But, for the most part I felt urged to do things for people without asking, and I resisted it, but at the same time I felt like I had an innate sense of whether or not it was OK. Like, if I was doing it, the person was unconsciously giving me permission. I don't generally read people without permission, but there are times when the info is just there without my prompting, and a few times curiosity got the better of me!
I've also had things try to stop me. One lady's abusive husband passed away, and his spirit didn't like me talking to her, but it didn't stop me. In those cases, I don't push thing, but if I'm still getting info, I keep going, despite them trying to intimidate me! I've never encountered a very forceful spirit, though! Nothing I couldn't handle.