I never wear blue jeans with a sport coat but I do wear other colored jeans with sport coats, mostly grey and khaki jeans. I have a tough time getting over the slob factor that blue jeans and sport coat have for me. It must be that Michael Moore guy who put that in my head. I think blue jeans and a jacket can look great if you are the right kind of guy with the right aura. You have to be a sharp guy. Hair, nails, shoes and everything, all sharp looking. And the jeans should be dark and not wrinkled up and baggy. IMO it takes a lot of work and preparation before you go out, more than I do on myself, to look good with this combo. Truth is, I have put on blue jeans and a jacket and really like what i see in the mirror. But I know I would be self conscious all day about so I don't go outside until I have changed into something else.