The phrase "are so dissimilar" is correct and usable in written English.
It can be used to emphasize the significant differences between two or more subjects.
Example: "The two paintings are so dissimilar that it's hard to believe they were created by the same artist."
Alternatives: "are very different" or "are quite unlike".
"But our two colts are so dissimilar," Bailey said.
Their sounds are so dissimilar that you have to strain to detect any vocal family resemblance.
It is hard to compare the impression Colby made with that of Darrow, they are so dissimilar.
Even if some of the material in the shows is the same, these singers are so dissimilar they might almost be saluting different composers.
Of course Denver, with its snowy winters and warm but wet summers, cannot learn much from Barcelona, with its Mediterranean climate, because they are so dissimilar.
This is considered to be because these phase pairs are so dissimilar that the maximum correlation does not always occur at the phase onsets.
This unnamed group show presents four artists whose politically inflected work is so dissimilar that the results are wonderfully discordant and refreshingly off-putting.
Both he and Warner will probably swing for the rafters from ball one once the Brisbane Test is under way, but in other senses their paths needn't be so dissimilar.
Moreover, the distinctive economic dilemmas of the 1930s were novel to Americans, largely because their historical experiences were so dissimilar from those of people in the rest of the world.
Critics of substance dualism claimed, or assumed without argument, that it concealed an explanatory gap, since it failed to explain how two substances that were so dissimilar could interact causally with each other.
She concluded that the Texan species was so dissimilar as to warrant its own genus, which she named Chorioactis.
