No. If he's with someone in my social circle, I won't go after him. If I've seen him spend time with her and think they're dating, I'll have no desire to go after him regardless of how good looking he is. But both of these apply if the girl is pretty too. I don't really judge based on how handsome or beautiful a person is. If he's with an ugly girl, there must be a reason.
Either scenario - I would think he sees someone for who they are and not whether they are hot or not. I would probably have more respect for him. UNLESS I found out he was going out with her just to get laid or something. Then I would be mad.
I don't think it would affect my likeliness to go out with him UNLESS I liked him in the first place and he was casually dating the ugly girl. But if they were in a relationship, I wouldn't mess with that.
No.If he is hot, I think damn he could do better, (me, lol) but I don't think less of him. In fact I might even think better of him for seeing past her looks or not feeling he has to go for a certain type of girl because society expects him to.