If the valves are deficient, venous return will become more difficult. If the valves become deficient in a particular area, than that area will have a problem in its venous return (swelling, oedema etc). This is for example the case with varicosities. This tends to occur in those people who, by profession, have to stand a long time (shopkeepers, teachers). Over the years, the valves will slowly deteriorate, expand, and blood will pool in those areas. These are visible as ugly swellings under the skin: varicosities.