First of all, what was up with Jane's amnesia about the guy? Was this mentioned in an earlier episode and I just forgot? I just don't find it realistic how she wasn't even sure if she'd recognize his face. Besides, the man is extremely tall - very difficult to mistake just anybody for him even if you tried.
Second, what "awful smell"? Perry had an awful smell emanating from him?
Well, first of all, she was brutally raped. Memory is a funny thing when you really really really wish you could stop remembering something, like a brutal rape.
Was what mentioned in an earlier episode?
As for him being extremely tall, it sure was a sign that they had tragically miscast the part (if he'd been of average build, maybe I wouldn't have known who it was, and deduced the whole "mystery" two episodes in), but in real life, it's not exactly a distinctive feature. Lots of tall guys around.
Second (third?), I'm guessing any smell coming from the guy who is brutally raping you would be awful. I'm not really sure why you even wonder but it could even just be his cologne.
It was six years ago, she only knew him for one night and never saw him again. I think it's totally possible to forget a face from that long ago, especially associated with that kind of trauma. But the second she did see him she remembered him.
I thought maybe the smell was liquor? It seemed like Perry was more violent when he was drinking (aka the climactic scene).