I will have to make sure to post my WIWs of my slouchy jeans that I'll be wearing to work :)!
I think the whole "dress like the job you want to have" thing is somewhat different for academics who have tenure. For me, a tenured associate professor who will be taking on an administrative role, the only place I'm heading is full professor. I can guarantee that no one will care about what sort of denim I've worn on meetings days when I am going up for full professor!
ETA: I agree that shredded, holey, ripped up jeans are not so professional, but I think that slouchy jeans that are somewhat dark and non-ripped (like yours, Makrame, and mine) are A-OK, at least in the academic settings I've been in.