jealous, distrustful, suspecting, doubting, questioning, wary, leery, doubtful, dubious, suspect, in doubt, without faith, skeptical, unbelieving, without belief, wondering.
Antonyms trusting*, trustful, without any doubt of.
not quite trustworthy, questionable, queer, suspect, irregular, unusual, uncommon, different, peculiar, open to question, out of line, shady, equivocal, overt, debatable, disputable.
Antonyms regular*, usual, common.
"suspicious." YourDictionary, n.d. Web. 24 May 2018. <http://thesaurus.yourdictionary.com/suspicious>.
suspicious. (n.d.). Retrieved May 24th, 2018, from http://thesaurus.yourdictionary.com/suspicious
Of dubious character:
Lacking trust or confidence: