善くも as opposed to よく


I found this line in the song,”三年目の浮気”:

> よくいうよ 惚れたお前の負けだよ How can you say that...you fell for me and lost

At first I thought it was the よく meaning often, but someone told me it was an
abbreviation of よくも (善くも), which is translated as "How dare you?" If this is
true, why does 善くも mean this?

If this is not the case, what does the よくいう mean here?

Here are some of the other lyrics:

> (男)馬鹿いってんじゃないよ お前と俺は ケンカもしたけど ひとつ屋根の下暮らして来たんだぜ
>
> Don't talk like that... Yes we fought, but we've been living under the same
> roof.
>
> 馬鹿いってんじゃないよ お前のことだけは 一日たりとも忘れたことなど なかった俺だぜ
>
> Don't say such things... It's not like there has been even one day where I
> forgot you.
>
> (女)よくいうわ いつもだましてばかりで 私が何んにも知らないとでも 思っているのね
>
> What are you saying?.. you're always deceiving me... And you think that I
> don't know?
>
> (男)よくいうよ 惚れたお前の負けだよ
>
> What are you saying?.. you fell for me and lost
>
> もてない男が好きなら 俺も考えなおすぜ
>
> If you really liked guys who saw no action, I'd have to think you over too

<http://www.youtube.com/watch?v=DgBvi-cZbJM>




[`よく`](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%82%88%E3%81%8F&dtype=0&dname=0ss&stype=1&index=120099400000&pagenum=1)
can be used as praise in regards to something which entails
difficulties/trouble in some contexts (this is separate to the "often/well"
meaning):

> **よく** まあ来られましたね！  
>  _How wonderful_ it is that you were able to come!

But it can also be used ironically in that sense, which I think is how it's
used in those lyrics:

> **よく(も)** まあそんなことが言えますね  
>  _How dare_ you say such a thing?  
>  (Literally something like " _How wonderful_ that you can say such a
> thing.")

[`よくも`](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%82%88%E3%81%8F%E3%82%82&dtype=0&dname=0ss&stype=0&index=120109300000&pagenum=1)
is a strengthened version of
[`よく`](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%82%88%E3%81%8F&dtype=0&dname=0ss&stype=1&index=120099400000&pagenum=1)
(according to
[Daijisen](http://dic.yahoo.co.jp/dsearch?enc=UTF-8&p=%E3%82%88%E3%81%8F%E3%82%82&dtype=0&dname=0na&stype=0&index=18941800&pagenum=1))
used to express surprise/blame at awful behavior. The `も` can be omitted and
have the same "how dare..." meaning in many contexts.

If you look at the [Progressive JE dictionary entry for
`よく`](http://dic.yahoo.co.jp/dsearch?p=%E3%82%88%E3%81%8F&enc=UTF-8&stype=0&dtype=3),
you'll see some more examples in the 5th and 6th definitions.

