I think Nutters answer best explains why homosexuals think of a bathroom as a great place to meet other homosexuals.The blessed aroma of fecal matter and associated discharges (urine, blood, etc.) create a soothing and often heartwarming atmosphere reminiscent of the conjugal bliss of sodomy. Enshrouded in the misty atmosphere thus provided, the activities thereby take on a viscerally affecting charm, transcending the mere mechanical bliss of the acts.
Think of it as a meme.