I wonder if some people want to be famous for 15 minutes and they don't care how, but yes it is baffling. If I lived in a dirty, cluttered house I wouldn't want it to be shown to millions of viewers as I'd be embarrassed.
OTOH, if someone suffers from some rare, dread disease or condition perhaps it can be helpful or informative to see that they can be helped with medical intervention in such programmes as Your Life in Their Hands, etc. Also, perhaps it can be demonstrated that the person with the condition may get some understanding from those of us who are lucky enough to enjoy good health.