Loathing is a feeling of complete disgust. Your loathing of the feeling of sand between your toes means that going to the beach isn't much fun for you.
If you have an utterly disgusted hatred of something, you have a loathing for it. A loathing of green vegetables can result in nutritional problems, and a loathing of little kids would make a person a pretty terrible babysitter. To loathe something is to abhor or strongly dislike it; the Old English root of both loathe and loathing is laðian, to be disgusted with.