Often customers who are used to purchasing supermarket coffee beans look for an oily bean as this tends to have the most flavour. This is true of mass-produced coffee beans, as what little flavour is left in the bean has matured into surface oils that will be available during brewing. Some industrial scale roasters actually add oil to give the impression of quality.
Fresh CoffeeBeanShop coffee that has been optimally slow roasted may show a small amount of surface sheen over time, but generally won’t be oily. This does not mean that the beans will lack a full flavour – quite the opposite. Slow roasted coffee is recognised as a process that produces the most flavour, industrial roasters can only achieve the same ‘punch’ by over-roasting beans to a charred (and often oily) state.