Yes, but how does one identify the homosexual priest (other than perhaps exaggerated mannerisms, and a penchant for color coordinated floral arrangements). There is no 'gay' gene.
We know there are gay priests. They slipped in or were invited by other gays in the seminaries and dioceses. Now, here is the conundrum. If the church bans the admission of admitted homosexuals, it may well force them to remain silent. If the church accepts them, it will open the floodgates to the more militant gays.
Until now, the issue was moot since all priests must practice a celibate lifestyle. This rule does not change ... unless they open the door to married priests.
If the clergyman is closeted, and most are, this will not be an easy task. However, this task is not impossible. Oaths; investigations where applicable... are a good start. Check out where the clergyman goes on his time off; whether he preaches against homosexality or is silent about it...Undercover investigations have worked as well. I have no reason to fear that in my life. But some out there do fear being exposed.