fly-by-night
adjective [ before noun ] informal disapproving uk/ˈflaɪ.baɪ.naɪt/ us/ˈflaɪ.baɪ.naɪt/
（公司或商人）不可靠的，无信用的
Fly-by-night companies or business people cannot be trusted because they are likely to get into debt and close down the business to avoid paying the debts or satisfying agreements.
a fly-by-night operator/organization 不可靠的经营者／机构