To answer your question, shoes are “income inelastic” if you do not cut back much on shoes when your income falls. They are “price inelastic” if you do not cut back much on shoes when their price rises. Something tells me you think shoes are inelastic in both respects.
I would argue that a more pertinent term here is “diminishing marginal utility”. The first pair of shoes protects your feet. All subsequent pairs of shoes are merely variety. I write without fear of contradiction when I suggest that the more shoes any one person has, the more time each pair will spend at home in the shoe cupboard.
Well yes, but I rather doubt that the ladies think in these terms. I am very far from being an expert in women's psychology, but even I know that a new pair of shoes does wonders for a girl's morale. And don't ever try to tell them otherwise.