minScale and maxScale values of 0 and Infinity do not make sense in OpenLayers, but they are used in WMS GetCapabilities 1.1.1 to indicate that there is no minScale or maxScale restriction. Assuming that the capability values for minScale and maxScale are passed as config options to a WMS layer, it is better to not set minScale and maxScale when 0 or Infinity are found in the ScaleHint.