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suspicious; dubious; unreliable
indecent; unseemly
あの店はいかがわしい雰囲気だ。
That shop has a suspicious atmosphere.
いかがわしい店には近づかない。
I don't go near unseemly establishments.
深夜に届いたメールの内容がいかがわしかった。
The content of the email that arrived late at night was suspicious.