untrustworthy (adj.)

• dangerous
• desultory
• doubtful
• dubious
• fly-by-night
• hazardous
• infirm
• insecure
• insubstantial
• irresponsible
• perilous
• precarious
• provisional
• questionable
• risky
• rocky
• shaky
• shifting
• shifty
• slippery
• temporary
• tentative
• ticklish
• tottery
• treacherous
• unassured
• uncertain
• undependable
• unhealthy
• unpredictable
• unreliable
• unsafe
• unsound
• unstable
• unsteady
• unsubstantial
• unsure
• untrusty