I actually like Yvonne and here's why...
Yes, I get she appeared as a bitch and not supportive to some, but the truth is she was the most realistic character. How many of you would actually believe someone saying the things Alice said in the way she said it? No matter how close the person was to you, you wouldn't (unless you are very religious or superstitious).
So to those who think she was a bitch, I say shame on you. Because you are calling every sane rational person a bitch since we wouldn't believe this *beep* either. I'm tired of seeing characters that believe the *beep* right away because it benefits the story. Like Alice's brother in part 4 saying that the high school kids are "dropping like flies" so what's he supposed to think? I know if there were mass suicides going on, in reality, people wouldn't be believing some chick that attributed them to some psychopath that killed children in their dreams to avenge his death. Same goes for just about every other friend character in the series and especially Lisa from the second part who treats Jesse like a victim even though he's got blood on his hands and admits to killing his friend. I wouldn't try to make him feel better or rationalize the situation. I'd call the cops!
Yes, we are expected to suspend our belief in reality while watching these movies, but I think that notion is mostly true for the dream sequences. If some dream killer were actually a menace, that wouldn't change most people's perceptions or beliefs in science which happens a lot in these films. The only thing that would change a person's perception would be proof which is exactly what Yvonne got when Freddy shoved her head into the hot tub and used her as bait for Alice. Then she finally believed, unlike all these other people who would be considered crazies for taking the word of someone like Alice after all the mysterious deaths.