It‘s not always bad~It just a special emotion between male-female. In general ，the relationship is better than friendship，lower than love (usually，theirs deeds looks like falling in love or will be falling in love .) For example： A male-female have a 暧昧 relationship,but the male has another girl friend. We often think that’s bad. A male-female look like have a 暧昧 relationship， but they don't recognize that they are falling in love and say they are just friend. In this case ，some one perhaps think is bad ，because they think they aren't honest . But if some one believe they are just good friend，the 暧昧 of course not bad. A male-female have a 暧昧 relationship from their childhood . And they become husband and wife. This 暧昧 is good，often we admire it .We have another world for it in this case .The world is 两小无猜. I am a Chinese ,so my English is poor . If my express has some mistakes ，please give some advice ，thank you.

暧昧 can be a noun and adjective. It basically means unclear attitude and situation.For example,when someone acts like he's into you but he hasn't confess, so there is 暧昧 between you and him.

a man and a woman are not a couple,but they do sth what a coulpe does except Kiss and sex,they are not in a relationship,they seem like friends,but sth they said or done beyond the friendship.

not just limited in the male-female relationship, other usings as follows: 对于A国家的内乱，周边国家的态度都很暧昧

曖昧 之本義是 含混不清、幽暗不明 引申為 行為不光明磊落，有不可告人的隱私 原義 並無限定使用於 兩性之交往 或情感 也可以使用於語意 想法等方面 如：「這個廣告語意曖昧，容易令人想入非非。」 限定於男女關係 是後人窄化其義了 真要討論 窄化意義後之男女曖昧關係 請見 http://tw.knowledge.yahoo.com/search/search_result?p=%E6%9B%96%E6%98%A7 這裡有各種說法