I can honestly say, I didn't find my spouse attractive when I met him the first time.
We met online: we had chatted and talked over the phone for hourseach day before meeting each other in real life. So far, I was attracted to everything about him: we shared interests, life goals, values, political and spiritual opinions, etc. I found his voice on the phone to be incredibly sexy, too. We were open about our mutual attraction to each other, and we agreed the first date ''IRL'' would be the ultimate test to know if we wanted to start a relationship together.
When I met him, I didn't know what to think. He was very shy and didn't speak much (it was easier for him to communicate through emails or by phone. He admitted later that it was because he felt intimidated by me). He was nervous, I told jokes to make him laugh, but I don't know. It wasn't what I had expected. After our first date, he drove me to my hotel (he lived 3 hours away so I stayed there for the weekend) and didn't feel attracted enough to kiss him goodnight. We hugged instead, and ... and then the magic happened! I felt so good in his arms, it just can't be described. I felt warm, comforted, protected, loved ... I didn't want this hug to stop. When I went to bed that night, I realized it meant something. I had never met someone who was so perfect for me, and felt so great in their arms.
The next day we had a day date at a local museum, and we flirted shamelessly all day. The chemistry was definitely there, once you removed a bit of shyness. I have since been attracted to my SO. :) Thankfully, because I would have missed such a great person and a great relationship if I had been stubborn about my first ''IRL'' impression.