Recently purchased one of these ($6.98 at Walmart with in-store pickup), but every time I used it "goop" would come out the joint between the Camco adapter and the sewer hose. Not good. Tried it with different hoses, same result. Contacted Camco, and they were VERY helpful - quickly sent me a replacement gasket. Problem is, there is no gasket where the leak was happening. Turns out the gasket was for the other end of the fitting. So obviously that did not solve the problem, although I really appreciated Camco's quick assistance.
Today I played around with it, trying to see what was going on, and FOUND THE PROBLEM! Turns out that it's possible to turn and snap the bayonet latches, even though the hose fitting is not fully inserted into the Camco adapter!! I suspect this is true of any sewer hose connector. I could actually see a gap where the hose connected to the Camco adapter! EWWWWWWWW!
So to prevent this problem, all you need to do is to make sure the hose connector is fully inserted in the Camco adapter before turning it to engage the bayonet tabs. It may take a wiggle or two. My problem is that I wasn't seeing it - the gap was on the underside, away from me. From now on I will connect the hose to the Camco adapter BEFORE hooking the adapter to my trailer's sewer outlet. That way I can visually inspect the joint and make sure it's seated correctly.
End of problem. Hope this will save someone else from spewing "goop".