Don't be fooled by those sweet words. You need to learn how to tell apart the good men from the bad ones!
ご質問ありがとうございます。
"Don't be fooled by those sweet words."=「甘い言葉に騙されないように。」
"You need to learn how to tell apart the good men from the bad ones!"=「良い男と悪い男を区別できるように学ぶ必要がある!」
(又は、"You need to cultivate your skills in telling apart the good men from the bad ones."=「良い男と悪い男を見分ける能力を養う必要がある」とも言えます。)
ご参考に。