Of course I have been reading around, and it bothers me that the lack of sympathy shown by Sam and Dean toward Bobby, which has bothered a lot of people, doesn't bother me. Then there is all this talk of love, for a show boasting the famous 'no chick-flick moments!' one-liner, the Show sports a surprising amount of chick-flick moments. Talking about irony and protesting too much.
Anyway, yesterday while I was washing veggies for dinner, I suddenly got it. Their apparent hostility toward Karen is born out of love and concern for Bobby. You know, if you equate Karen Singer with Sam's Demon Blood problem, then look how they have dealt with that, their attitude is actually quite true to their characters. I am going to go out on a limb and say it is a guy thing, they are better at not being overtly sympathetic, and tough love.
As for Karen, I never thought any differently. I think even Dean said as much (something to the effect of 'we care about you and don't want her eating your brains.' at least it was along those lines). It's just I understand Bobby's POV, too, and it broke my heart for him, because he's one of my fav characters on the show (besides Sam). It's why I'm always going YAY! BOBBY over at my journal ;)
I think it is kindda funny that Dean has offered twice to off someone's loved one, and was turned down both times. He runs with a tough crowd.