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Clouds May Hide Water On Alien Worlds (sciencemag.org)
sciencehabit writes: Astronomers have discovered about 2000 planets around other stars, but they have few hard facts about what they are like, such as the contents of their atmospheres. Now, a team of astronomers using the Hubble and Spitzer space telescopes have gathered enough data (abstract) to compare 10 large exoplanets, finding a range of atmosphere types, and to propose a solution to an early mystery of exoplanet atmospheres: why some don't seem to have enough water. Study lead David Sing said, "I’m really excited to finally 'see' this wide group of planets together, as this is the first time we’ve had sufficient wavelength coverage to compare multiple features from one planet to another. We found the planetary atmospheres to be much more diverse than we expected, and this significantly progresses our understanding of what makes up these planets and how they were created."
They have some idea what the clouds consist of, based on how they reflect/filter their sun's light. It's silicates and other minerals, not water. The point is if such a cloudy planet has water oceans, we would still not see the water signature because the clouds are in the way.