It depends on WHY I'm talking to them. I have ~160 friends on this site, very few of which have photos up at all and even fewer are attractive. I'm only here to talk to people and give my opinion / advice though so there's no reason to discriminate against anyone based on their appearance. Though, hypothetically, if I were looking for someone to date, I would most definitely discriminate based on appearance.
I look at photos overall to see what the individual looks like.That's why it is important to look at more than one photo,and to even post multiple photos.HOWEVER,I know what I am interested in,and I can tell overall if I think the individual fits within the guidelines of what I like...by looking at those pics,and usually,I'm right.So yes,it is very possible that If I am talking to someone via internet dating,and I don't think they fit the criteria of what I am looking for,I WILL probably stop talking to him...unless we can just be friends.