doubtful that something should be relied upon — as in "The argument relies on a dubious assumption."
doubtful that something is morally proper — as in "The company is accused of using dubious sales practices to influence minors."
bad or of questionable value — as in "The state has the dubious distinction of the highest taxes."
doubtful or uncertain — as in "She is dubious about making the change."
Bert Tozer, Albert R. Tozer, cashier and vice-president of the Wheatsylvania State Bank, auditor and vice-president of the Tozer Grain and Storage Company, treasurer and vice-president of the Star Creamery, was not in the least afflicted by the listening dubiousness of his parents.
Chapter 9 (69% in)
There are no more uses of "dubious" in Arrowsmith.