Really, there are only so many times you can bring a pile of seaweed-laden gold-dust into the surveyor's office with arousing the suspicions of the authorities. "Mr. Hoover," the field officer would report, "we've got another 'sea-gold' incident, this time at Grover's Mill."
And a detective's salary? Puh-lease; this is J'onn J'onnz we're talking about. Do you know what long distance calls to Mars cost, even to your Fave Five? Mars needs money, folks, not women.
Fortunately, JJ arrived during the repressive 1950s. Being a manhunter, JJ had a ready and obvious source of income:
Blackmailing closeted gays for money.
Oh, and sexual favors. Disturbing things, that involved toys, and props, and fishing tackle.
And the less said about the "dropped soap in the prison" incident, the better...
Of course, this was just a phase J'onn was going through, which ended when he discovered sweet sweet octopus love.