Arousing doubt; questionable; open to suspicion.
"is dubious" is a correct and usable phrase in written English. It is commonly used to express doubt or suspicion. For example, you could say "The quality of the service is dubious."
Honduras is dubious.
Mr. O'Reilly is dubious.
This claim is dubious.
Guessing is dubious.
Mr Seehofer is dubious.
Mr. Miller is dubious.
Dr. McKenna is dubious.
This argument is dubious.
Even that, however, is dubious.
The claim is dubious.
The whole episode is dubious, however.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com