I want all attendees to know that I LOVE when they come to talk to me after the session ends. Best moment ever. And even if you didn't like something, by all means let me know so I can get better. I also don't believe that speakers "generally" dislike it.
Secondly, attendees: it might be tempting to join 'the line' after the talk has finished, but speakers don't generally prefer this way of Q&A. They have to gather their stuff and make way for the next speaker, and they've just finished a talk" They're a bit swamped.