Some people really want to be noticed and appreciated by these famosos. If they act like they like you, they are in fact acting. You're one in a few hundred that day, one in thousands at all the cons put together. If you go for an autograph and they don't really make eye contact with you, be strong and care not whether some actor in some tv show pretended to care about you for ten seconds. You are of inestimable worth, at least to yourself, and probably to several others in this world. So William Shatner didn't look at you. It's ok.