My book explains that あれで can be used to indicate mild surprise, and gives some example sentences. They all make sense to me except this one:
今日{きょう}の食堂{しょくどう}の定食{ていしょく}、あれでよく改善{かいぜん}したって言{い}えるよね。まるで豚{ぶた}のえさだよ。
In the first sentence, the speaker seems to be pleasantly surprised at the quality of the cafeteria meal. But in the second, he says it's like pig food. Is the first sentence sarcastic? Is something else going on there?
A half literal, half free translation (in the sense of "worst of both worlds"):
今日の食堂の定食、あれでよく改善したって言えるよね。まるで豚のえさだよ。
Regarding today's lunch special, with that they have some nerve to say that they improved. It's quite simply pig food.
あれで doesn't express pleasant surprise. よく言える is, I guess, where you got lost. It doesn't mean "being well able to say", but rather "how could you say that?".
A sentence from ALC for comparison:
そんなこと、よく言えるわね？
How can you ask me to do that?
I think you may misunderstand the meaning of "よく". In this sentence, "よく" doesn't mean "good".
"あれでよく[改善]{かいぜん}したって[言]{い}えるよね" means "Why do they say that it was improved!"
