Lots of websites use class names like floatleft, clearfloat, alignright, small, center etc that describe the
It depends, sometimes it makes sense just to add a class to let an element float. The problem with the semantic approach is that you will end up ball of mud of css classes. Sure, names like redLink or blackHeader have to be banned but sometimes you will need little helpers like "clear" or "floatLeft".
Read this article of Nicole Sullivan who explain this in deep.