Mesh quality control in SMESH is destined for visual control of the generated mesh.
Application of a definite quality control consists of usage of the corresponding algorithm, which calculates a value of a definite geometric characteristic (Area, Length of edges, etc) for all meshing elements, composing your mesh. Then all meshing elements are colored according the calculated values. The reference between the coloring of the meshing elements and these calculated values is shown with the help of a scalar bar, which is displayed near the presentation of your mesh.
In SMESH you have at your disposal the following mesh quality controls: