This would be better phrased as "Unlike a misused prostate, your suspicion 'holds water'."

But, at very least, do your readership the courtesy of adding the necessary comma between the main and subordinate clauses: "Your suspicion holds water, unlike a misused prostate." Or you could even use a hyphen or ellipses in place of the comma.

Otherwise, if you're looking to pay homage to Douglas Adams "The ships hung in the sky in much the same way that bricks don't" then the best way to phrase it would be "Your suspicion holds water like a misused prostate."

It's purely stylistic but, at the end of the day, do you want to go to the high-society gala in an off-the-peg, doublebreasted two-piece or a bespoke, tailored tuxedo?

Did I do it right? I did use the 'private note' function correctly, yes?