In Superman's case, I don't even see the need for a secret identity, he's Superman!!
He should just say; "Hi the name's Clark, just provide me all my basic earthly needs and I'll save your asses every five minutes. And I don't work weekends."
That's the difference between the DC and Marvel Universe. For the most part Marvel's superheroes let everyone one know who they are. In the DC universe the secret identity seems much more important.
The older I get the harder it is for me to suspend disbelief that people don't know Clark Kent is Superman.
Most of Marvels heroes had the secret ID thing too. Spider-man still does. Iron Man, Cap and DD held on to theirs for a pretty long time. Thor's was probably the earliest one to fade out. Some of them went to elaborate measures to preserve them. (Cap especially). The FF are the only ones who truly had no secret IDs at the start. Well, maybe Dr. Strange, but even his "heroic" ID was sorta secret.