Shoes are indeed a valuable source of information about a person. I knew at least one BH case manager who really paid attention to them.
Shoes are expensive, very durable, and typically one of those items that people have only a few pairs of. So while someone can easily change their outfit to match a situation, place, or mood for the day, they may be less likely to change their shoes to match more than a basic purpose.
And shoes tend to accumulate evidence of where someone's been. Are they muddy, dusty, spit-polished?
Personally, I own about five pair of shoes. I have a pair of Oxford dress shoes, a very nice pair of white New Balance with hook-and-loop, some hiking boots I picked up at JC Penney, and a few others. My clothing, on the other hand, is mostly Adidas and Columbia and some tee shirts, but I don't own any Adidas or Columbia shoes. So you can tell a lot about me, no matter what I'm wearing, by studying my shoes for a while.
I met another BH professional who said he owned 52 pairs of Crocs. He said that he'd kicked an addiction habit, but it seems he traded something unhealthy for perhaps a less-detrimental dependence on collecting shoes. To each his own, I suppose, and surely a lot of information could be gleaned about this fellow if you paid attention to which pair of Crocs he'd selected for the day.