The word "trustworthy" means "worthy of trust". Depending on the context, it could have the synonyms reliable, dependable, steadfast, or loyal.
reliable
trustworthy
The synonym for "not suspicious" is "trustworthy" or "reliable."
respectable, notable, eminent, honored, trustworthy, reputable
trustworthy, sensible, mature, reliable, dependable
Believable, unquestionable, undoubted, palpable...
Trustworthy, fair or honest. (there are more but I am not going to do this all day)
honorable, reliable, dependable, truthful, honest
This phrase means that one is honest, trustworthy, that they can keep a promise, their "word is as good as gold."
Some synonyms are: decent, honest, honorable, principled, pure, trustworthy, truthful, uncorrupt, upright
"Dubious" is primarily an adjective that means doubtful or uncertain. It is not a synonym or antonym on its own; rather, it describes a state of skepticism or lack of trust. Synonyms for "dubious" include "suspicious" or "questionable," while antonyms would be "certain" or "trustworthy."
Trustworthy, generous, kind, thoughtful, loyal, good listener, caring, loving, reliable.