I have a gaming group in which this term "丑八怪" is being used a lot along with the 眼皮底下, anyway all the letters look similar.
2 Answers
According to this article:
「醜八怪」用以形容外貌醜陋的人。它來源於「揚州八怪」。 揚州八怪指的是趣味相投畫風相似的一批人,他們是:李蟮、汪士慎、高翔、金農、鄭燮、黃慎、李方膺、羅聘、高鳳翰、華岩、閔貞、邊壽民、陳撰、楊法、李勉等諸人。(在中文裡「八」往往用作虛數詞,表示數量多,並不意味「揚州八怪」只有八個人。)其中尤以鄭燮、金農、汪士慎更著名。這些人在當時所謂的正統畫派眼裡一是做人不合時宜、我行我素,二是作畫我從我法、推陳出新。所以被篾成為「醜八怪」。然而,他們的怪異又入情入理,很被廣大百姓喜愛,因此,一方面被主流畫家和上層社會所攻擊、不容,一方面又深受大眾喜愛,名氣大振。
原文網址: https://kknews.cc/culture/p9myee.html
In short, there were eight weird painters in Yangzhou, they were nicknamed 「揚州八怪」, The mainstream artists did not like them and some called them 「醜八怪」
醜 referred to their 'ugly style' -- some mainstream artists thought so
怪 referred to 怪人 (eccentric person)
In modern times, the term 醜八怪 is used as a derogatory term for "ugly person" or "ugly creature"
As for 眼皮底下 (literally means under the eyelids) has the same meaning as "under the nose" in English
"丑八怪" means An/the ugly person(s) acting in a strange/eccentric way/manner.
The direct translation of "眼皮底下" is "below eyelid", however, it really refers to "see" (看), as below eyelid is the eyeball that performs the function - see.
Let's try to put these two phrases together to make better sense:
"眼皮底下淨是丑八怪" = "放眼望(看)去淨是丑八怪" - "All I can see are ugly weirdos", or "Look around, all are ugly weirdos".