Being too much of a comic book snob way back when, I didn't watch L&C when it was on the air. It took my daughter becoming a teenager and getting interested in romance stories to make me watch the DVDs, which she got for Christmas, '09.
The first thing that caught my attention as I watched the pilot and the first episode was that there was no suspension of disbelief necessary for the story. During the first season and several episodes of the second season, the longer hair on CK makes a difference.
When the glasses come off and the hair is pushed back there is the illusion of an age difference between the two identities. It still amuses me to watch the scene where Clark turns into Kal-El right behind Lois' back.
With what looks like a five year age difference between the identities why would anyone look beyond their similarities?
I have to assume from the DVD commentaries that the appearance of the cape becoming visually important was a reason why a shorter hair cut was necessary (to withstand the force of the air compressors.) Unfortunately, the illusion vanished with the shorter, more professional hair style.
Just my opinion.

Robert