fly-by-night
adjective
[ ˈflʌɪbʌɪnʌɪt ]
• unreliable or untrustworthy, especially in business or financial matters.
• "cheap suits made by fly-by-night operators"
Similar:
unreliable,
undependable,
irresponsible,
untrustworthy,
dishonest,
deceitful,
not to be trusted,
dubious,
double-dealing,
treacherous,
traitorous,
two-faced,
unfaithful,
duplicitous,
dishonourable,
unprincipled,
unscrupulous,
corrupt,
underhand,
iffy,
shady,
shifty,
slippery,
crooked,
dodgy,
bent,
shonky,
fly-by-night
noun
• an unreliable or untrustworthy person.