The phrase "are sometimes characterized" is correct and usable in written English.
It can be used when describing the occasional traits or features of a subject or phenomenon.
Example: "These species are sometimes characterized by their vibrant colors and unique patterns."
Alternatives: "are occasionally defined" or "are sometimes described".
Premodern Buddhists are sometimes characterized as veritable "mind scientists" whose insights anticipate modern research on the brain and mind.
PMCB systems are found throughout industry, e.g., power generating systems, parallel computing systems, transportation systems, and are sometimes characterized by their common cause failures.
Various contemporaries of Mayer's, such as Louise Glück and Frank Bidart, are sometimes characterized as "post-confessional" for extending the line of candid psychic inquiry that began with Sylvia Plath and Robert Lowell.
Women from the Shan minority and other ethnic minority groups in northeastern Myanmar are telling stories of rapes by the military that are sometimes characterized by sadism and that human rights groups say appear to be authorized and systematic.
Organometallic coordination compounds are sometimes characterized by "sandwich" structures, in which two molecules of an unsaturated cyclic hydrocarbon, which lacks one or more hydrogen atoms, bond on either side of a metal atom.
Secondary qualities are sometimes characterized as being reducible to primary qualities; sometimes, as powers to bring about ideas of certain sorts; sometimes, as merely subjective and as lacking any reality.
"It is not nearly as invasive or as sinister as it is sometimes characterized to be," he said.
She had been Bonnard's muse since 1893, and toward the end of their life together she was sometimes characterized as his jailer.
"With respect to what is sometimes characterized as taking out Saddam," he added, "I never saw a plan that was going to take him out.
The American criminal-justice system is sometimes characterized as a rabbit hole, as is U.S. health insurance, Verizon tech support, and anything having to do with United Airlines.
— which is sometimes characterized by critics as a punishment for Church staff members who get out of line — is a volunteer program for self-improvement.
