I take notice of shoes all the time but I don't care that much. It depends on the situation. If I'm in a club, it's going to be the last thing I notice. If I'm at a more formal event, then it's good to keep them clean at least.
I do notice shoes as that sorta gives me insight on their style and look. And style leads me to their personality type. So it's all sorta linked. For example if I saw a guy with converse shoes I'd automatically think "okay this is my kinda guy" just because of the connotation that converse or vans for example have with skaters/rock/punk. Obviously I'm generalizing. But on the other hand if I saw guys wearing DC sorta shoes I'd think "hip hop" or gangster style. If I see a young lad wearing grandpa kinda shoes I'd think "vintage", "hipster" or something along those lines. So shoes can sorta give off a vibe.