あの人ひと、すごく誠実せいじつだよね。

ano hito, sugoku seijitsu da yo ne.

That person is really sincere, huh. casual

彼かれはお客様きゃくさまにいつも誠実せいじつでした。

kare wa okyakusama ni itsumo seijitsudeshita.

He was sincere with customers, always. neutral