Single words for low degree of trust

semireliable / semi-reliable (adj.)

(chiefly computing) Partly or somewhat reliable; having a fair degree of reliability. Wiktionary

Words like reliable: semireliable definition.org

Earliest example found:

After the fall of the glorious Icelandic Republic...the Sagas subsequently drifted down into only semi-reliable records; and later were little less historical than the half-fiction, half-fact of the Sagawriter of modern times—Sir Walter Scott. George Browning; The Edda Songs and Sagas of Iceland (1876)

I have been informed on semireliable authority that the irrigating canals of central Asia , situated in the cotton-growing districts , are being very considerably extended and improved; ... US Bureau of Foreign Commerce; Special Consular Reports (1891)

But until it can be procured in some reliable or semireliable form this will be impossible. Annual Report of the State Pathology Laboratory p.135 (1899)

This semireliable narrator is the most difficult to detect because he is the source of both trustworthy and misleading information. Linda Willem; Galdós's Segunda Manera (1998)

Besides, do you really want to decide whether you should remain married to a cheating spouse on the basis of a semireliable skin test? Kenneth Rosenberg; Infidelity (2018)

The C18 biography itself, however, undercuts its argument for government sabotage by describing Donaldson's car earlier in the biography, calling it a “semireliable automobile that just about managed to get him from A to B” as a way of ... Kirsten Dyck; Reichsrock (2017)

Road from Phari to Lachen/Lachung is also reported to be nearing completion (semi-reliable source). Claude Arpi; The End of an Era (2020)

The specification allows the user to determine whether multicast transfers are unreliable or semireliable. Dave Kosiur; IP Multicasting (1998)

Dennis was acting fidgety. I put him on license-plate duty. It gave him something to do. It gave me a semireliable sentry—scouring the passing jumble of numbers and letters for the ones we needed to rear. James Siegel; Deceit (2006)

After a documented analysis of the seven major forecasting domains, however, its author, William Sherden (1998) concluded that the forecasts that are commonly used as a basis for planning and strategy are only semireliable. Jaap van Ginneken; Collective Behaviour and Public Opinion (2003)

Other semireliable prosodic and phonological cues accompanied the phrasestructure grammar: word length, stress, and pitch. Scott Johnson; Neoconstructivism: The New Science of Cognitive Development (2009)

Directly across two-lane Sunrise Highway Highway S1 is the start of Noble Canyon Trail, which strikes west–southwest only 50 yards to a semireliable water supply. Laura Randall; Pacific Crest Trail (2020)

A nearby spring provides a semireliable water source. D. Lillard and G. Hicks; Exploring the Appalachian Trail (2013)

Should you need it, there is:

semireliably (adv.)

Although absence of evidence might not be evidence of absence, the fact that left IFG involvement was observed only semireliably in blocked cyclic naming studies of semantic interference suggests the need for ... G. de Zubicaray and N. Schiller; The Oxford Handbook of Neurolinguists (2019)

Indeed, the unit pattern (that's the meme) is defined by what's semireliably copied—for example, the gene's DNA sequence is semireliably copied during meiosis, whereas whole chromosomes or organisms are not reliably copied at all. William Calvin; How Brains Think (2014)

Indeed, that which is semireliably copied pretty much defines the pattern of interest. Diederik Aerts et al.; Einstein Meets Magritte (2012)

And yes, Virginia, there is a

semireliability (n.)

By World War I, submarines had advanced to the point of semireliability, but crews who found themselves trapped on the ocean floor were still doomed to drown or suffocate, for deepwater rescue apparatus didn't exist. Jim Ignasher; Rhode Island Disasters (2010)

Data streaming applications such as ticker tape and news feeds, which are one to many, need only semireliability sometimes and group sizes can be large—in the tens of thousands or even millions. Jessica Keyes; Financial Services Information Systems

Less common (NGram) is half-reliable (adj.)

The winds blow him chance bits of news in an irregular, half-reliable way. The Living Age, Vol. 100, p.409 (1869)

Half-reliable is simply not reliable, like a partner who tells you he or she is 50% faithful; it is a contradiction in terms. Michael Blastland; The Hidden Half: How the World Conceals its Secrets (2019)

semi-trustworthy (adj.) pops up once in a while.

He then adverted to Helena, and began extolling her to the skies; but by this time the dwelling of his semi-trustworthy friend was visible, and reaching it they knocked him up. Richard Bedingfield; Moll Cutpurse (1846)

The readers of Miss Bird's fascinating, but only semi-trustworthy work, will not be like to read Mr. Dickson's comely volume. The Literary World (1889)

I have tried to disentangle from a mass of only semi-trustworthy records the true origin of the well-known saying: "He has Seius' Horse in his stable." Basil Tozer; The Horse in History (1908)

However in many cases the organization may be semi-honest or completely dishonest. In the case of semi-trustworthy (also called semi-honest) partners, organizations may have to play games to extract data. H. Chen and C. Yang; Intelligence and Security Informatics (2008)

You can also mix and match—you'll find half-trustworthy as well.